nicole honoré - Academia.edu (original) (raw)
Papers by nicole honoré
PubMed, 1983
We have detected a 1.6 kb RNA species in the polysomes of cells infected with the m1 strain of Mo... more We have detected a 1.6 kb RNA species in the polysomes of cells infected with the m1 strain of Moloney Murine Sarcoma Virus. This RNA contains the cellular transforming sequences (mos) as well as sequences located at both ends of the viral genome and is devoid of other internal viral sequences. This RNA appears to be spliced and might function as the messenger for the transforming protein of the Moloney Murine Sarcoma Virus.
Journal of Virology, 1990
Moloney murine sarcoma virus ts110 possesses a thermosensitive splicing defect. By continuously g... more Moloney murine sarcoma virus ts110 possesses a thermosensitive splicing defect. By continuously growing nonproducer cells at the nonpermissive temperature, a new class of revertant cells, termed 6m3, that had lost the thermosensitive splicing defect was produced, and six distinct clones were selected. These cell clones were transformed at either permissive or restrictive temperatures. Unlike parental 6m2 cells, which contain two virus-specific RNA species of 4.0 and 3.5 kilobases (kb) at temperatures permissive for transformation, the 3.5-kb RNA was the only virus-specific RNA species detected in 6m3 clones. No new v-mos-containing DNA fragment was observed in Southern blot analysis of these cell clones compared with parental 6m2 cells, indicating that the 3.5-kb RNA was a splicing product rather than a direct transcript. Moreover, these cells expressed P85gag-mos but not P58gag at any temperature. The reversion of the phenotype in 6m3 cell clones appears to be the result of a selec...
médecine/sciences, 1995
chef de clinique-assistant, semice de fmeumologie, hôpital Saint-Louis. V. Clos son : ancien inte... more chef de clinique-assistant, semice de fmeumologie, hôpital Saint-Louis. V. Clos son : ancien interne des h ôp itaux de Pa ris.
Nouvelle revue française d'hématologie, 1993
The Rab branch of the Ras-related guanine nucleotide (GTP/GDP)-binding proteins currently include... more The Rab branch of the Ras-related guanine nucleotide (GTP/GDP)-binding proteins currently includes at least thirty related members which are involved in the intracellular vesicular transport along the secretory and endocytic pathways in eukaryotic cells. We have demonstrated the overexpression of the Rab2 protein in peripheral blood mononuclear cells from patients exhibiting Sézary syndromes and other lymphoid and myeloid malignancies. Several lines of evidence suggest that the Rab2 overexpression can be related not to leukemic cells but to a subset of peripheral lymphocytes with a CD2+ phenotype. Our results provide strong evidences for the implication of a small GDP/GTP binding protein in immunological events associated with neoplastic states. The precise cellular population involved in this process remains to be determined.
Leukemia, 1993
The Rab branch of the Ras-related GTP/GDP-binding proteins currently includes at least 25 related... more The Rab branch of the Ras-related GTP/GDP-binding proteins currently includes at least 25 related members which are involved in the intracellular vesicular transport along the secretory and endocytic pathways in eukaryotic cells. The overexpression of the Rab2 protein in peripheral mononuclear cells is demonstrated from 13 out of 17 patients exhibiting a Sézary syndrome. Moreover, this phenomenon is detectable in other lymphoid and myeloid malignancies. Several lines of evidence are shown suggesting that the Rab2 overexpression can be related not to leukemic cells but to a subset of peripheral lymphocytes with a CD2+ phenotype. Our results provides strong evidence for the implication of a small GDP/GTP-binding protein in immunological events associated with neoplastic states. The precise cellular population involved in this process remains to be determined.
Archaeopress Publishing Ltd eBooks, Oct 4, 2023
Les Cahiers De L Aars, 2010
L'inventaire des representations rupestres de tortues au Sahara permet de proposer des identi... more L'inventaire des representations rupestres de tortues au Sahara permet de proposer des identifications zoologiques, et de tenter des rapprochements avec les attestations archeologiques de cet animal.
Les Cahiers De L Aars, 2009
Parmi les archers peints et graves au Sahara, nombreux sont ceux qui semblent masques. Parmi ces ... more Parmi les archers peints et graves au Sahara, nombreux sont ceux qui semblent masques. Parmi ces derniers, ceux qui sont dotes d'une queue postiche semblent ne former qu'une petite minorite parmi toutes les representations d'archers du Sahara Central.
Les Cahiers De L Aars, 2007
L'examen de quelques abris tassiliens peu visites donne l'occasion de completer leur docu... more L'examen de quelques abris tassiliens peu visites donne l'occasion de completer leur documentation, et de tenter quelques reflexions generales sur les personnages masques ou theranthropes.
Les Cahiers De L Aars, 2004
Les Cahiers de l' …, 2010
Résumé/Abstract Un nouvel ensemble d'images rupestres enrichit notablement la documentation ... more Résumé/Abstract Un nouvel ensemble d'images rupestres enrichit notablement la documentation sur les zones de Taserert-Iharhaien, dans une région tassilienne peu fréquentée. La qualité des nombreuses peintures en style d'Iheren est y remarquable et la ...
Les Cahiers De L Aars, 2009
Presentation d'une abondante serie de documents en provenance d'une region peu visitee. P... more Presentation d'une abondante serie de documents en provenance d'une region peu visitee. Plusieurs n'apparaissent qu'apres le traitement informatique des photographies, selon une procedure controlee. Le repertoire iconographique tassilien en ressort notablement enrichi.
Oncogene, Jan 18, 1995
The immediate-early gene rhoB codes for a small GTP-binding protein highly homologous to the RhoA... more The immediate-early gene rhoB codes for a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to regulate the assembly of focal adhesions and stress fibers in response to growth factors, the function of RhoB remains unknown. In a first attempt to elucidate its function, we examined the variation of the RhoB protein expression in response to induction of its mRNA. We report here that RhoB is an unstable protein rapidly and transiently induced by growth factors in PC12 and HeLa cells. Moreover, RhoB protein accumulation is periodic through the cell cycle. First detected at the G1/S phase transition, the level of the RhoB protein is maximal during the S phase and declines at the S/G2-M transition. This timing suggests that RhoB plays a role in the G1/S phase transition and/or in the S phase of the cell cycle. We also confirm here a vesicular and perinuclear localization of the endogenous RhoB protein induced by growth factors.
Proceedings of the National Academy of Sciences of the United States of America, Jan 13, 2006
The pathogenesis of acute promyelocytic leukemia involves the transcriptional repression of maste... more The pathogenesis of acute promyelocytic leukemia involves the transcriptional repression of master genes of myeloid differentiation by the promyelocytic leukemia-retinoic acid receptor alpha (PML/RARA) oncogene. PML-enforced RARA homodimerization allows the tighter binding of corepressors, silencing RARA target genes. In addition, homodimerization dramatically extends the spectrum of DNA-binding sites of the fusion protein compared with those of normal RARA. Yet, any contribution of these two properties of PML/RARA to differentiation arrest and immortalization of primary mouse hematopoietic progenitors was unknown. We demonstrate that dimerization-induced silencing mediator of retinoid and thyroid receptors (SMRT)-enhanced binding and relaxed DNA-binding site specificity are both required for efficient immortalization. Thus, enforced RARA dimerization is critical not only for triggering transcriptional repression but also for extending the repertoire of target genes. Our studies exe...
Proceedings of the National Academy of Sciences, 1999
Analyzing the pathways by which retinoic acid (RA) induces promyelocytic leukemia/retinoic acid r... more Analyzing the pathways by which retinoic acid (RA) induces promyelocytic leukemia/retinoic acid receptor α (PML/RAR α ) catabolism in acute promyelocytic leukemia (APL), we found that, in addition to caspase-mediated PML/RAR α cleavage, RA triggers degradation of both PML/RAR α and RAR α . Similarly, in non-APL cells, RA directly targeted RAR α and RAR α fusions to the proteasome degradation pathway. Activation of either RAR α or RXR α by specific agonists induced degradation of both proteins. Conversely, a mutation in RAR α that abolishes heterodimer formation and DNA binding, blocked both RAR α and RXR α degradation. Mutations in the RAR α DNA-binding domain or AF-2 transcriptional activation region also impaired RAR α catabolism. Hence, our results link transcriptional activation to receptor catabolism and suggest that transcriptional up-regulation of nuclear receptors by their ligands may be a feedback mechanism allowing sustained target-gene activation.
Oncogene, 2000
Most acute promyelocytic leukemia (APL) cases are associated with recurrent translocations betwee... more Most acute promyelocytic leukemia (APL) cases are associated with recurrent translocations between the gene of retinoic receptor alpha and that of PML (t(15;17)) or PLZF (t(11;17)). PML localizes onto discrete intranuclear domains, the PML-nuclear bodies, and displays antioncogenic and pro-apoptotic properties. PLZF encodes a transcription factor belonging to the POZ/domain and KruÈ ppel zinc ®nger (POK) family which interacts directly with PML. PLZF is related to another POK protein, LAZ3(BCL6), which is structurally altered, and presumably misexpressed, in many non-Hodgkin lymphoma (NHL) cases. PLZF and LAZ3 share many functional properties: both inhibit cell growth, concentrate into punctated nuclear subdomains and are sequence-speci®c transcriptional repressors recruiting a histone deacetylaserepressing complex. Given these similarities, we tested whether both proteins could be targeted by each other. Here, LAZ3 and PLZF are shown to colocalize onto nuclear dots. Moreover, truncated derivatives of one protein, which display a diuse nuclear localization, are recruited onto nuclear dots by the full-length other. The colocalization and the reciprocal`rescue' is the result of a direct interaction between LAZ3 and PLZF, as indicated by yeast two hybrid assays, in vitro immunoprecipitations, and GST pull down experiments. In contrast to LAZ3 homomerization, LAZ3/PLZF heteromerization in yeast does not solely depend on POZ/POZ contacts but rather also relies on interactions between the two zinc ®nger regions and`cross' contacts between the zinc ®nger region and the POZ domain of each partner. Likewise, LAZ3 shows some colocalization with the PLZF partner PML upon stable overexpression of both proteins in CHO cells and interacts with PML in yeast. Finally, endogenous LAZ3 and PLZF are co-induced and partially colocalized in myeloid MDS cells. These data indicate that a physical interaction between LAZ3 and PLZF underlies their simultaneous recruitment onto multiproteic nuclear complexes, presumably involved in transcriptional silencing and whose integrity (for APL) and/or function (for APL and NHL) may be altered in oncogenesis. Oncogene (2000) 19, 6240 ± 6250.
Journal of General Virology, 1983
Intracellular polyadenylated viral RNA from cells infected by five different isolates of Moloney ... more Intracellular polyadenylated viral RNA from cells infected by five different isolates of Moloney murine sarcoma virus (Mo-MuSV) was analysed by gel transfer hybridization. Genomic sizes of 4-6 kilobases (kb) for the ml-MuSV isolate, 5-2 kb for the m3and 124-MuSV, 6.1 kb for the HT1-MuSV and 6-7 kb for the 78-A1-MuSV were determined. With the exception of the ml strain, subgenomic RNA species were found in cells infected by the various isolates. However, no common subgenomic RNA containing v-mos sequences could be characterized. Each transformed cell line expressed a different set of viral RNA species in terms of size and structure.
Journal of Biological Chemistry, 1996
RhoB is a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to... more RhoB is a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to regulate the assembly of focal adhesions and stress fibers in response to growth factors, the function of RhoB remains unknown. We have reported that the transient expression of the endogenous RhoB protein is regulated during the cell cycle, contrasting with the permanent RhoA protein expression (1). Using the yeast two-hybrid system to characterize proteins interacting with RhoB, we identified a new mouse Rho GDP dissociation inhibitor, referenced as RhoGDI-3. The NH 2-terminal ␣ helix of RhoGDI-3 is strongly amphipatic and differs thus from that found in previously described bovine, human, and yeast RhoGDI proteins and mouse and human D4/ Ly-GDIs. Contrary to the cytosolic localization of all known GDI proteins, acting on Rab or Rho, RhoGDI-3 is associated to a Triton X-100-insoluble membranous or cytoskeletal subcellular fraction. In the two-hybrid system, RhoGDI-3 interacts specifically with GDP-and GTP-bound forms of post-translationally processed RhoB and RhoG proteins, both of which show a growthregulated expression in mammalian cells. No interaction is found with RhoA, RhoC, or Rac1 proteins. We show that GDI-3 is able to inhibit GDP/GTP exchange of RhoB and to release GDP-bound but not GTP-bound RhoB from cell membranes.
PubMed, 1983
We have detected a 1.6 kb RNA species in the polysomes of cells infected with the m1 strain of Mo... more We have detected a 1.6 kb RNA species in the polysomes of cells infected with the m1 strain of Moloney Murine Sarcoma Virus. This RNA contains the cellular transforming sequences (mos) as well as sequences located at both ends of the viral genome and is devoid of other internal viral sequences. This RNA appears to be spliced and might function as the messenger for the transforming protein of the Moloney Murine Sarcoma Virus.
Journal of Virology, 1990
Moloney murine sarcoma virus ts110 possesses a thermosensitive splicing defect. By continuously g... more Moloney murine sarcoma virus ts110 possesses a thermosensitive splicing defect. By continuously growing nonproducer cells at the nonpermissive temperature, a new class of revertant cells, termed 6m3, that had lost the thermosensitive splicing defect was produced, and six distinct clones were selected. These cell clones were transformed at either permissive or restrictive temperatures. Unlike parental 6m2 cells, which contain two virus-specific RNA species of 4.0 and 3.5 kilobases (kb) at temperatures permissive for transformation, the 3.5-kb RNA was the only virus-specific RNA species detected in 6m3 clones. No new v-mos-containing DNA fragment was observed in Southern blot analysis of these cell clones compared with parental 6m2 cells, indicating that the 3.5-kb RNA was a splicing product rather than a direct transcript. Moreover, these cells expressed P85gag-mos but not P58gag at any temperature. The reversion of the phenotype in 6m3 cell clones appears to be the result of a selec...
médecine/sciences, 1995
chef de clinique-assistant, semice de fmeumologie, hôpital Saint-Louis. V. Clos son : ancien inte... more chef de clinique-assistant, semice de fmeumologie, hôpital Saint-Louis. V. Clos son : ancien interne des h ôp itaux de Pa ris.
Nouvelle revue française d'hématologie, 1993
The Rab branch of the Ras-related guanine nucleotide (GTP/GDP)-binding proteins currently include... more The Rab branch of the Ras-related guanine nucleotide (GTP/GDP)-binding proteins currently includes at least thirty related members which are involved in the intracellular vesicular transport along the secretory and endocytic pathways in eukaryotic cells. We have demonstrated the overexpression of the Rab2 protein in peripheral blood mononuclear cells from patients exhibiting Sézary syndromes and other lymphoid and myeloid malignancies. Several lines of evidence suggest that the Rab2 overexpression can be related not to leukemic cells but to a subset of peripheral lymphocytes with a CD2+ phenotype. Our results provide strong evidences for the implication of a small GDP/GTP binding protein in immunological events associated with neoplastic states. The precise cellular population involved in this process remains to be determined.
Leukemia, 1993
The Rab branch of the Ras-related GTP/GDP-binding proteins currently includes at least 25 related... more The Rab branch of the Ras-related GTP/GDP-binding proteins currently includes at least 25 related members which are involved in the intracellular vesicular transport along the secretory and endocytic pathways in eukaryotic cells. The overexpression of the Rab2 protein in peripheral mononuclear cells is demonstrated from 13 out of 17 patients exhibiting a Sézary syndrome. Moreover, this phenomenon is detectable in other lymphoid and myeloid malignancies. Several lines of evidence are shown suggesting that the Rab2 overexpression can be related not to leukemic cells but to a subset of peripheral lymphocytes with a CD2+ phenotype. Our results provides strong evidence for the implication of a small GDP/GTP-binding protein in immunological events associated with neoplastic states. The precise cellular population involved in this process remains to be determined.
Archaeopress Publishing Ltd eBooks, Oct 4, 2023
Les Cahiers De L Aars, 2010
L'inventaire des representations rupestres de tortues au Sahara permet de proposer des identi... more L'inventaire des representations rupestres de tortues au Sahara permet de proposer des identifications zoologiques, et de tenter des rapprochements avec les attestations archeologiques de cet animal.
Les Cahiers De L Aars, 2009
Parmi les archers peints et graves au Sahara, nombreux sont ceux qui semblent masques. Parmi ces ... more Parmi les archers peints et graves au Sahara, nombreux sont ceux qui semblent masques. Parmi ces derniers, ceux qui sont dotes d'une queue postiche semblent ne former qu'une petite minorite parmi toutes les representations d'archers du Sahara Central.
Les Cahiers De L Aars, 2007
L'examen de quelques abris tassiliens peu visites donne l'occasion de completer leur docu... more L'examen de quelques abris tassiliens peu visites donne l'occasion de completer leur documentation, et de tenter quelques reflexions generales sur les personnages masques ou theranthropes.
Les Cahiers De L Aars, 2004
Les Cahiers de l' …, 2010
Résumé/Abstract Un nouvel ensemble d'images rupestres enrichit notablement la documentation ... more Résumé/Abstract Un nouvel ensemble d'images rupestres enrichit notablement la documentation sur les zones de Taserert-Iharhaien, dans une région tassilienne peu fréquentée. La qualité des nombreuses peintures en style d'Iheren est y remarquable et la ...
Les Cahiers De L Aars, 2009
Presentation d'une abondante serie de documents en provenance d'une region peu visitee. P... more Presentation d'une abondante serie de documents en provenance d'une region peu visitee. Plusieurs n'apparaissent qu'apres le traitement informatique des photographies, selon une procedure controlee. Le repertoire iconographique tassilien en ressort notablement enrichi.
Oncogene, Jan 18, 1995
The immediate-early gene rhoB codes for a small GTP-binding protein highly homologous to the RhoA... more The immediate-early gene rhoB codes for a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to regulate the assembly of focal adhesions and stress fibers in response to growth factors, the function of RhoB remains unknown. In a first attempt to elucidate its function, we examined the variation of the RhoB protein expression in response to induction of its mRNA. We report here that RhoB is an unstable protein rapidly and transiently induced by growth factors in PC12 and HeLa cells. Moreover, RhoB protein accumulation is periodic through the cell cycle. First detected at the G1/S phase transition, the level of the RhoB protein is maximal during the S phase and declines at the S/G2-M transition. This timing suggests that RhoB plays a role in the G1/S phase transition and/or in the S phase of the cell cycle. We also confirm here a vesicular and perinuclear localization of the endogenous RhoB protein induced by growth factors.
Proceedings of the National Academy of Sciences of the United States of America, Jan 13, 2006
The pathogenesis of acute promyelocytic leukemia involves the transcriptional repression of maste... more The pathogenesis of acute promyelocytic leukemia involves the transcriptional repression of master genes of myeloid differentiation by the promyelocytic leukemia-retinoic acid receptor alpha (PML/RARA) oncogene. PML-enforced RARA homodimerization allows the tighter binding of corepressors, silencing RARA target genes. In addition, homodimerization dramatically extends the spectrum of DNA-binding sites of the fusion protein compared with those of normal RARA. Yet, any contribution of these two properties of PML/RARA to differentiation arrest and immortalization of primary mouse hematopoietic progenitors was unknown. We demonstrate that dimerization-induced silencing mediator of retinoid and thyroid receptors (SMRT)-enhanced binding and relaxed DNA-binding site specificity are both required for efficient immortalization. Thus, enforced RARA dimerization is critical not only for triggering transcriptional repression but also for extending the repertoire of target genes. Our studies exe...
Proceedings of the National Academy of Sciences, 1999
Analyzing the pathways by which retinoic acid (RA) induces promyelocytic leukemia/retinoic acid r... more Analyzing the pathways by which retinoic acid (RA) induces promyelocytic leukemia/retinoic acid receptor α (PML/RAR α ) catabolism in acute promyelocytic leukemia (APL), we found that, in addition to caspase-mediated PML/RAR α cleavage, RA triggers degradation of both PML/RAR α and RAR α . Similarly, in non-APL cells, RA directly targeted RAR α and RAR α fusions to the proteasome degradation pathway. Activation of either RAR α or RXR α by specific agonists induced degradation of both proteins. Conversely, a mutation in RAR α that abolishes heterodimer formation and DNA binding, blocked both RAR α and RXR α degradation. Mutations in the RAR α DNA-binding domain or AF-2 transcriptional activation region also impaired RAR α catabolism. Hence, our results link transcriptional activation to receptor catabolism and suggest that transcriptional up-regulation of nuclear receptors by their ligands may be a feedback mechanism allowing sustained target-gene activation.
Oncogene, 2000
Most acute promyelocytic leukemia (APL) cases are associated with recurrent translocations betwee... more Most acute promyelocytic leukemia (APL) cases are associated with recurrent translocations between the gene of retinoic receptor alpha and that of PML (t(15;17)) or PLZF (t(11;17)). PML localizes onto discrete intranuclear domains, the PML-nuclear bodies, and displays antioncogenic and pro-apoptotic properties. PLZF encodes a transcription factor belonging to the POZ/domain and KruÈ ppel zinc ®nger (POK) family which interacts directly with PML. PLZF is related to another POK protein, LAZ3(BCL6), which is structurally altered, and presumably misexpressed, in many non-Hodgkin lymphoma (NHL) cases. PLZF and LAZ3 share many functional properties: both inhibit cell growth, concentrate into punctated nuclear subdomains and are sequence-speci®c transcriptional repressors recruiting a histone deacetylaserepressing complex. Given these similarities, we tested whether both proteins could be targeted by each other. Here, LAZ3 and PLZF are shown to colocalize onto nuclear dots. Moreover, truncated derivatives of one protein, which display a diuse nuclear localization, are recruited onto nuclear dots by the full-length other. The colocalization and the reciprocal`rescue' is the result of a direct interaction between LAZ3 and PLZF, as indicated by yeast two hybrid assays, in vitro immunoprecipitations, and GST pull down experiments. In contrast to LAZ3 homomerization, LAZ3/PLZF heteromerization in yeast does not solely depend on POZ/POZ contacts but rather also relies on interactions between the two zinc ®nger regions and`cross' contacts between the zinc ®nger region and the POZ domain of each partner. Likewise, LAZ3 shows some colocalization with the PLZF partner PML upon stable overexpression of both proteins in CHO cells and interacts with PML in yeast. Finally, endogenous LAZ3 and PLZF are co-induced and partially colocalized in myeloid MDS cells. These data indicate that a physical interaction between LAZ3 and PLZF underlies their simultaneous recruitment onto multiproteic nuclear complexes, presumably involved in transcriptional silencing and whose integrity (for APL) and/or function (for APL and NHL) may be altered in oncogenesis. Oncogene (2000) 19, 6240 ± 6250.
Journal of General Virology, 1983
Intracellular polyadenylated viral RNA from cells infected by five different isolates of Moloney ... more Intracellular polyadenylated viral RNA from cells infected by five different isolates of Moloney murine sarcoma virus (Mo-MuSV) was analysed by gel transfer hybridization. Genomic sizes of 4-6 kilobases (kb) for the ml-MuSV isolate, 5-2 kb for the m3and 124-MuSV, 6.1 kb for the HT1-MuSV and 6-7 kb for the 78-A1-MuSV were determined. With the exception of the ml strain, subgenomic RNA species were found in cells infected by the various isolates. However, no common subgenomic RNA containing v-mos sequences could be characterized. Each transformed cell line expressed a different set of viral RNA species in terms of size and structure.
Journal of Biological Chemistry, 1996
RhoB is a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to... more RhoB is a small GTP-binding protein highly homologous to the RhoA protein. While RhoA is known to regulate the assembly of focal adhesions and stress fibers in response to growth factors, the function of RhoB remains unknown. We have reported that the transient expression of the endogenous RhoB protein is regulated during the cell cycle, contrasting with the permanent RhoA protein expression (1). Using the yeast two-hybrid system to characterize proteins interacting with RhoB, we identified a new mouse Rho GDP dissociation inhibitor, referenced as RhoGDI-3. The NH 2-terminal ␣ helix of RhoGDI-3 is strongly amphipatic and differs thus from that found in previously described bovine, human, and yeast RhoGDI proteins and mouse and human D4/ Ly-GDIs. Contrary to the cytosolic localization of all known GDI proteins, acting on Rab or Rho, RhoGDI-3 is associated to a Triton X-100-insoluble membranous or cytoskeletal subcellular fraction. In the two-hybrid system, RhoGDI-3 interacts specifically with GDP-and GTP-bound forms of post-translationally processed RhoB and RhoG proteins, both of which show a growthregulated expression in mammalian cells. No interaction is found with RhoA, RhoC, or Rac1 proteins. We show that GDI-3 is able to inhibit GDP/GTP exchange of RhoB and to release GDP-bound but not GTP-bound RhoB from cell membranes.