Multiple Members of the Mitogen-activated Protein Kinase Family Are Necessary for PED/PEA-15 Anti-apoptotic Function

Abstract

293 kidney embryonic cells feature very low levels of the anti-apoptotic protein PED. In these cells, expression of PED to levels comparable with those occurring in normal adult cells inhibits apoptosis induced by growth factor deprivation and by exposure to H2O2 or anisomycin. In PED-expressing 293 cells (293PED), inhibition of apoptosis upon growth factor deprivation was paralleled by decreased phosphorylation of JNK1/2. In 293PED cells, decreased apoptosis induced by anisomycin and H2O2 was also accompanied by block of JNK1/2 and p38 phosphorylations, respectively. Impaired activity of these stress kinases by PED correlated with inhibition of stress-induced Cdc-42, MKK4, and MKK6 activation. At variance with JNK1/2 and p38, PED expression increased basal and growth factor-stimulated Ras-Raf-1 co-precipitation and MAPK phosphorylation and activity. Treatment of 293PED cells with the MEK inhibitor PD98059 blocked ERK1/2 phosphorylations with no effect on inhibition of JNK1/2 and p38 activities. Complete rescue of JNK and p38 functions in 293PED cells by overexpressing JNK1 or p38, respectively, enabled only partial recovery of apoptotic response to growth factor deprivation and anisomycin. However, simultaneous rescue of JNK and p38 activities accompanied by block of ERK1/2 fully restored these responses. Thus, PED controls activity of the ERK, JNK, and p38 subfamilies of MAPKs. PED anti-apoptotic function in the 293 cells requires PED simultaneous activation of ERK1/2 and inhibition of the JNK/p38 signaling systems by PED. 293 kidney embryonic cells feature very low levels of the anti-apoptotic protein PED. In these cells, expression of PED to levels comparable with those occurring in normal adult cells inhibits apoptosis induced by growth factor deprivation and by exposure to H2O2 or anisomycin. In PED-expressing 293 cells (293PED), inhibition of apoptosis upon growth factor deprivation was paralleled by decreased phosphorylation of JNK1/2. In 293PED cells, decreased apoptosis induced by anisomycin and H2O2 was also accompanied by block of JNK1/2 and p38 phosphorylations, respectively. Impaired activity of these stress kinases by PED correlated with inhibition of stress-induced Cdc-42, MKK4, and MKK6 activation. At variance with JNK1/2 and p38, PED expression increased basal and growth factor-stimulated Ras-Raf-1 co-precipitation and MAPK phosphorylation and activity. Treatment of 293PED cells with the MEK inhibitor PD98059 blocked ERK1/2 phosphorylations with no effect on inhibition of JNK1/2 and p38 activities. Complete rescue of JNK and p38 functions in 293PED cells by overexpressing JNK1 or p38, respectively, enabled only partial recovery of apoptotic response to growth factor deprivation and anisomycin. However, simultaneous rescue of JNK and p38 activities accompanied by block of ERK1/2 fully restored these responses. Thus, PED controls activity of the ERK, JNK, and p38 subfamilies of MAPKs. PED anti-apoptotic function in the 293 cells requires PED simultaneous activation of ERK1/2 and inhibition of the JNK/p38 signaling systems by PED. PED is a 15-kDa protein with almost ubiquitous expression (1.Araujo H. Danziger N. Cordier J. Glowinski J. Chneiweiss H. J. Biol. Chem. 1993; 268: 5911-5920Abstract Full Text PDF PubMed Google Scholar, 2.Condorelli G. Vigliotta G. Iavarone C. Caruso M. Tocchetti C.G. Andreozzi F. Tecce M.F. Cafieri A. Formisano P. Beguinot L. Beguinot F. EMBO J. 1998; 17: 3858-3865Crossref PubMed Scopus (139) Google Scholar). cDNA sequencing led to the identification of a canonical death effector domain (DED) 1The abbreviations used are: DEDdeath effector domainGSTglutathione S-transferaseERKextracellular signal-regulated kinaseMAPKmitogen-activated protein kinaseJNKc-Jun N-terminal kinaseHAhemagglutininDMEMDulbecco's modified Eagle's mediumCNF1cytotoxic necrotizing factor 1CRIBCdc-42/Rac-interactive binding motifPAKp21-activated kinase at PED N terminus (3.Condorelli G. Vigliotta G. Cafieri A. Trencia A. Andalò P. Oriente F. Miele C. Caruso M. Formisano P. Beguinot F. Oncogene. 1999; 18: 4409-4415Crossref PubMed Scopus (138) Google Scholar, 4.Muzio M. Chinnaiyan A.M. Kischkel F.C. O'Rourke K. Shevchenko A. Ni J. Scaffidi C. Bretz J.D. Zhang M. Gentz R. Mann M. Krammer P.H. Peter M. Dixit V.M. Cell. 1996; 85: 817-827Abstract Full Text Full Text PDF PubMed Scopus (2741) Google Scholar). More recently, we and others (3.Condorelli G. Vigliotta G. Cafieri A. Trencia A. Andalò P. Oriente F. Miele C. Caruso M. Formisano P. Beguinot F. Oncogene. 1999; 18: 4409-4415Crossref PubMed Scopus (138) Google Scholar, 5.Kitsberg D. Formstecher E. Fauquet M. Kubes M. Cordier J. Canton B. Pan G. Rolli M. Glowinski J. Chneiweiss H. J. Neurosci. 1999; 19: 8244-8251Crossref PubMed Google Scholar) demonstrated that the DED of PED binds the DED of both FAS-associated death domain (FADD) and caspase 8 (FLICE). Through this mechanism, PED inhibits FLICE activation by tumor necrosis factor-α and FasL, thereby blocking the apoptotic effects of these cytokines. It has subsequently been shown that PED potentiates phosphorylation of the ERKs through a Ras-dependent mechanism (6.Ramos J.W. Hughes P.E. Renshaw M.W. Schwartz M.A. Formstecher E. Chneiweiss H. Ginsberg M.H. Mol. Biol. Cell. 2000; 11: 2863-2872Crossref PubMed Scopus (59) Google Scholar). PED also anchors the ERKs in the cytoplasm, preventing phosphorylation of their nuclear susbstrates and restraining cell proliferation (7.Formstecher E. Ramos J.W. Fauquet M. Calderwood D.A. Hseieh J. Canton B. Nguyen X. Barnier J. Camonis J. Ginsberg M. Chneiweiss H. Dev. Cell. 2001; 1: 239-250Abstract Full Text Full Text PDF PubMed Scopus (258) Google Scholar). These findings suggest that PED may feature a broad function in control of cell survival. However, the molecular mechanisms involved in PED action have only partially been elucidated. death effector domain glutathione S-transferase extracellular signal-regulated kinase mitogen-activated protein kinase c-Jun N-terminal kinase hemagglutinin Dulbecco's modified Eagle's medium cytotoxic necrotizing factor 1 Cdc-42/Rac-interactive binding motif p21-activated kinase Mitogen-activated protein kinases (MAPKs) play a major role in mediating cellular responses to a variety of extracellular stimuli, including death and survival signals (8.Davis R.J. J. Biol. Chem. 1993; 268: 14553-14556Abstract Full Text PDF PubMed Google Scholar, 9.Robinson M.J. Cobb M.H. Curr. Opin. Cell Biol. 1997; 9: 180-186Crossref PubMed Scopus (2286) Google Scholar). MAPKs include at least three main subgroups: the extracellular signal-regulated kinases (ERK1/2 or p42/44MAPK), the c-Jun N-terminal kinases (p46/54JNK), and p38MAPK. While structurally related, MAPK families undergo activation in response to extracellular stimuli through distinct upstream dual specificity kinases, thereby functioning in separate MAPK cascades (10.Davis R.J. Trends Biochem. Sci. 1994; 19: 470-473Abstract Full Text PDF PubMed Scopus (917) Google Scholar, 11.Kyriakis J. Banerjee P. Nikolakaki E. Dai T. Rubie E. Ahmad M. Avruch J. Woodgett J. Nature. 1994; 369: 156-160Crossref PubMed Scopus (2414) Google Scholar). The Raf/ERK kinase1/2/ERK1/2 cascade is stimulated by mitogenic and survival stimuli, largely through the Ras-Raf-1-dependent pathway (12.Ichijo H. Oncogene. 1999; 18: 6087-6093Crossref PubMed Scopus (473) Google Scholar, 13.L'Allemain G.L. Her J.H. Wu J. Sturgil T.W. Weber M.J. Mol. Cell. Biol. 1992; 12: 2222-2229Crossref PubMed Scopus (46) Google Scholar). At variance, p46/54JNK and p38MAPKare primarily activated by cellular stresses including oxidative agents, UV irradiation, hypoxia, proinflamatory cytokines, and anisomycin (14.Ip Y.T. Davis R.Y. Curr. Opin. Cell Biol. 1998; 10: 205-219Crossref PubMed Scopus (1382) Google Scholar, 15.Ishikawa Y. Kitmura M. Biochem. Biophys. Res. Commun. 1999; 264: 696-701Crossref PubMed Scopus (72) Google Scholar). Exposure to these agents often results in cell apoptosis (16.Cross T.G. Scheel-Toellner D. Henriquez N.V. Deacon E. Salmon M. Lord J.M. Exp. Cell Res. 2000; 256: 34-41Crossref PubMed Scopus (618) Google Scholar). Dual specificity kinases activating p46/54JNK are MAPK kinases 4 and 7 (MKK4 and MKK7), while MKK3 and MKK6 were proved to activate p38MAPK. MAPKs phosphorylate and activate a variety of cytoplasmic and nuclear substrates, including transcription factors. Despite the dicotomy in the main action of ERKs and stress kinases, current evidence indicates that ERKs and p46/54JNK-p38MAPK cooperate in inducing cells to survive or to die. Activation of the stress kinase cascade, alone, may not be sufficient to induce apoptosis under all circumstances (17.Xia Z. Dickens M. Raingeaud J. Davis R.J. Greenberg M. Science. 1995; 270: 1326-1331Crossref PubMed Scopus (5036) Google Scholar). Also, concomitant inactivation of survival signals appears to be necessary for enabling p46/54JNK and p38MAPK induction to cause cell death (17.Xia Z. Dickens M. Raingeaud J. Davis R.J. Greenberg M. Science. 1995; 270: 1326-1331Crossref PubMed Scopus (5036) Google Scholar, 18.Gupta K. Kshirsagar S. Li W. Gui L. Ramakrishnan S. Gupta P. Law P.Y. Hebbel R.P. Exp. Cell Res. 1999; 247: 495-504Crossref PubMed Scopus (344) Google Scholar, 19.Shan R. Price J.O. Gaarde W.A. Monia B.P. Krantz S.B. Zhao Z.J. Blood. 1999; 12: 4067-4076Crossref Google Scholar, 20.Berra E. Diaz-Meco M.T. Moscat J. J. Biol. Chem. 1998; 273: 10792-10797Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar, 21.Huang Y. Hutter D. Liu Y. Wang X. Sheikh S.M. Chan M.L. Holbrook N.J. J. Biol. Chem. 2000; 275: 18234-18242Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). It appears therefore that the balance between the ERK and the p46/54JNK-p38MAPK signaling systems is critical for inducing the cell to die or survive. However, the molecular mechanisms responsible for tuning the ratio of activities in these cascades are largely elusive. For instance, there is little information on whether checkpoint proteins exist in the cell that foster survival signal transduction through the ERK pathway while inhibiting p46/54JNK-p38MAPK signaling or vice versa. Answering this question will greatly help in the understanding how the cells control their own survival. In the present report we show that PED inhibits p46/54JNK and p38MAPK signaling and protects cells from stress-induced apoptosis. More importantly, we report that full PED anti-apoptotic action requires both ERK activation and inhibition of p46/54JNK-p38MAPK function, indicating that PED represents a major MAPK regulatory protein, which gathers antiapoptotic signals toward the cell machinery. Media, sera, antibiotics for cell culture, and the LipofectAMINE reagent were from Invitrogen. Rabbit polyclonal antibodies toward ERK1/2, p38, and JNK/SAPK were purchased from Santa Cruz, Inc. (Santa Cruz, CA). All phosphokinase antibodies were from New England Biolabs Inc. (Beverly, MA), and PED antibodies have been described previously (2.Condorelli G. Vigliotta G. Iavarone C. Caruso M. Tocchetti C.G. Andreozzi F. Tecce M.F. Cafieri A. Formisano P. Beguinot L. Beguinot F. EMBO J. 1998; 17: 3858-3865Crossref PubMed Scopus (139) Google Scholar). The HA-tagged JNK-1 and GST-tagged MKK6 cDNA plasmids were generously donated by Dr. S. Gutkind (National Institutes of Health, Bethesda, MD) and the GST-CRIB cDNA by Dr. P. Di Fiore (Istituto Europeo di Oncologia, Milan, Italy). The c-Jun cDNA has been reported previously (22.Musti A.M. Treier M. Bohmann D. Science. 1997; 275: 400-402Crossref PubMed Scopus (408) Google Scholar). SDS-PAGE reagents were purchased from Bio-Rad, and radiochemicals, Western blotting, and ECL reagents were from Amersham Biosciences. All other chemicals were from Sigma. The 293 human kidney embryonic cells were grown in DMEM supplemented with 10% fetal calf serum, 100 IU/ml penicillin, 100 IU/ml streptomycin, and 2% l-glutamine in a humidified CO2 incubator. A pcDNA3 expression vector containing the Myc-tagged PED cDNA was generated by first amplifying PED wild-type cDNA with the following two primers: PED5′ (5′-GGCCGGTACCGCCAGAGCGCGCGGGGCAGTGTG-3′) and 3′MycPEDB (5′-CGCGGATCCTCACAGATCCTCTTCTGAGATGAGTTTTTGTTCGGCCTTCTTCTTCGGTGGGGGAGCCAATTTGATGATCTCTT-3′), carrying the KpnI and the BamHI restriction sites, respectively. The amplification product was then cloned in the pcDNA3 plasmid and sequence verified using the T7Sequencing Kit by Amersham Biosciences. The construct was in 293 cells using the in 2.Condorelli G. Vigliotta G. Iavarone C. Caruso M. Tocchetti C.G. Andreozzi F. Tecce M.F. Cafieri A. Formisano P. Beguinot L. Beguinot F. EMBO J. 1998; 17: 3858-3865Crossref PubMed Scopus (139) Google was using at the of of and c-Jun were by the LipofectAMINE to the cells were in to and for with of cDNA and of LipofectAMINE in of DMEM supplemented with fetal calf was for The medium was then with DMEM with 10% and cells for For the cells were in the or the of or with anisomycin or H2O2 or 100 PD98059 in the of the was then by to E. N. 1999; PubMed Scopus Google or using the to the For these the cells were in 4 100 10% 1 100 1 for at 4 were at for proteins were by SDS-PAGE and on with the and were by ECL to the MAPK activity was in reported previously P. Oriente F. F. Caruso M. Miele C. A. Andreozzi F. Vigliotta G. G. Beguinot F. Mol. Cell. Biol. 2000; PubMed Scopus Google Scholar). cells were in and by at for of the were with MAPK and phosphorylation were by of the protein the phosphorylation 1 1 and were for at by on and on were with by in and the was by For of Cdc-42, cells were in the or the of cytotoxic necrotizing factor 1 for and in 100 1 1 and were then for at 4 in the of of in of binding 1 were with and then in by for 4 and at for were by SDS-PAGE and with 293 human embryonic kidney cells were with a Myc-tagged PED of cells were and three of and were in with or PED antibodies that the expression of PED in these cells was increased by with control cells, those with the plasmid or the 293 cells The cells feature very low levels of PED. a protein the levels of PED expression in the were comparable with those in and not on deprivation of cells induced a in In these cells, was upon of upon and At variance, no was in cells to In these cells, apoptosis only by The in the of in response to was in the two other not PED we the effects of the stress kinase anisomycin and in and control shown in with anisomycin for increased apoptosis by in and cells, In these cells, with induced a in apoptosis. In cells there was a inhibition in the apoptotic responses to all of these agents, with the control cells inhibition of apoptosis was in the other two of In cell the JNK and p38 play a major role in signaling apoptosis and undergo phosphorylation and activation in responses to growth factor and oxidative stress R. Price J.O. Gaarde W.A. Monia B.P. Krantz S.B. Zhao Z.J. Blood. 1999; 12: 4067-4076Crossref Google Scholar, 20.Berra E. Diaz-Meco M.T. Moscat J. J. Biol. Chem. 1998; 273: 10792-10797Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar, 21.Huang Y. Hutter D. Liu Y. Wang X. Sheikh S.M. Chan M.L. Holbrook N.J. J. Biol. Chem. 2000; 275: 18234-18242Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). In control 293 cells, anisomycin also induced a in phosphorylation of the activation of JNK and phosphorylation was by in with the control cells with no in JNK expression to deprivation increased JNK phosphorylation in effect at and was in the The in JNK phosphorylation upon anisomycin or was paralleled by a decreased phosphorylation of the JNK c-Jun in the with control cells on Western with and deprivation of control cells also increased phosphorylation of p38 activation by and A and of p38 by and deprivation were and in with the and cells very results not action on p38 and control cells were to H2O2 for The cells were and of cell proteins were with or with p38 antibodies the cells were in the or the of for the and cell proteins were with antibodies were by ECL and The shown are of and three In cells, PED ERK1/2 signaling through the pathway (6.Ramos J.W. Hughes P.E. Renshaw M.W. Schwartz M.A. Formstecher E. Chneiweiss H. Ginsberg M.H. Mol. Biol. Cell. 2000; 11: 2863-2872Crossref PubMed Scopus (59) Google Scholar). therefore that increased ERK1/2 activity may be responsible for inhibiting JNK and p38 function in 293 in cells, from 293 PED-expressing cells a increased co-precipitation with In the 293 cells a in ERK1/2 phosphorylation and activity and in ERK phosphorylation and activity in response to were in these cells, with no in ERK1/2 In both the and the control cells, inhibition of the ERK upstream kinase MEK with PD98059 blocked basal and ERK activities PD98059 no effect on the activation of JNK by anisomycin in cells PD98059 not recovery of p38 phosphorylation by in PED-expressing with wild-type cells and to cells with the plasmid Thus, ERK alone, not for the inhibition of JNK and p38 functions in JNK and p38 have been reported to be induced by the signaling cascade in response to agents M. H. P. N. T. Gutkind Cell. 1995; Full Text PDF PubMed Scopus Google Scholar). In 293 cells, M. J. A. K. G. 1999; PubMed Google Scholar) increased the of the domain of kinase with by These effects not in PED-expressing 293 cells, of the activation on kinases and MKK6 and were also increased by and by anisomycin and was the for the these effects were in the cells, that PED may JNK and p38 activation by blocking signaling through the pathway at upstream were no in the expression levels of Cdc-42, MKK4, and MKK6 A and in with the control the that of JNK and p38 activation is responsible for PED anti-apoptotic we to JNK and p38 function in PED-expressing 293 the cells with the HA-tagged GST-tagged or with both Western with and antibodies that these activated JNK and p38 kinases to almost in and in control cells indicating that kinase in their inhibition by PED. of JNK-1 with the c-Jun cDNA in a in c-Jun phosphorylation with the cells with c-Jun alone, both in and in control cells In the control cells, of JNK-1 or MKK6 increased apoptosis in response to deprivation by of these two kinases no In the cells, of or both a in cell PED inhibition with the cells at the Thus, full activation of JNK and p38 function in these cells, apoptosis that in the that the inhibition of JNK and p38 by PED in 293 cells not fully for PED anti-apoptotic therefore whether induction of ERK1/2 in cells may also to from while not for the inhibition of JNK and this we blocked ERK activity with the PD98059 Treatment of cells with alone, no in in control or in PED-expressing In control cells overexpressing JNK-1 PD98059 apoptotic response by in cells overexpressing JNK-1 PD98059 increased apoptosis to levels to the control were cell apoptosis was induced by Thus, PED from stress-induced apoptosis in 293 cells to on the simultaneous induction of ERK activity and inhibition of JNK and p38 have PED a protein, which and tumor necrosis apoptosis through In the present we show that PED a function, survival and anti-apoptotic signals to the cell through the ERK and the that PED in 293 kidney cells inhibits apoptosis by oxidative and anisomycin PED phosphorylation and activation of JNK and p38 by these agents, indicating role of decreased signaling through the in PED from stress-induced apoptosis. with this mechanism, expression of JNK and p38 activities the to stress-induced apoptosis in 293 In with the block of stress-induced activation of JNK and p38, their upstream activating kinases and MKK6 were also blocked in In in these cells, PED inhibits co-precipitation with the domain of that levels of PED may these that PED may induction of JNK and p38 stress kinases by at a very in their activation It is that PED binds and inhibits with However, we not co-precipitation of PED with not PED may by with or with a protein upstream in the signaling the mechanism of PED activation of JNK and p38 stress kinases will the identification of which is in in by Ramos (6.Ramos J.W. Hughes P.E. Renshaw M.W. Schwartz M.A. Formstecher E. Chneiweiss H. Ginsberg M.H. Mol. Biol. Cell. 2000; 11: 2863-2872Crossref PubMed Scopus (59) Google Scholar) in cells, PED ERK1/2 in a Ras-dependent ERK activation by PED also in 293 cells, accompanied by that of mechanisms in the signaling Activation of the ERKs was not responsible for the inhibition of JNK and p38 function in cells levels of PED. block of ERK activity with the PD98059 inhibitor no in inactivation in the 293PED PD98059 not apoptosis by deprivation in wild-type 293 cells almost no or in Thus, ERK alone, is to stress-induced apoptosis in these of activities in 293 cells is not sufficient not recovery of to stress apoptosis. the full apoptotic effect of deprivation and anisomycin in 293 cells were restored by simultaneous block of ERK activation and of led to that in 293 cells, PED a major survival protein, which controls the major mitogen-activated protein and in these cells, stress-induced activation of apoptotic on the concomitant inhibition of ERK survival pathway and on activation of death signaling through the of kinases in with the inhibition of the ERK pathway has been in a of cell systems cell death (17.Xia Z. Dickens M. Raingeaud J. Davis R.J. Greenberg M. Science. 1995; 270: 1326-1331Crossref PubMed Scopus (5036) Google Scholar, 18.Gupta K. Kshirsagar S. Li W. Gui L. Ramakrishnan S. Gupta P. Law P.Y. Hebbel R.P. Exp. Cell Res. 1999; 247: 495-504Crossref PubMed Scopus (344) Google Scholar, 19.Shan R. Price J.O. Gaarde W.A. Monia B.P. Krantz S.B. Zhao Z.J. Blood. 1999; 12: 4067-4076Crossref Google Scholar, 20.Berra E. Diaz-Meco M.T. Moscat J. J. Biol. Chem. 1998; 273: 10792-10797Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar, 21.Huang Y. Hutter D. Liu Y. Wang X. Sheikh S.M. Chan M.L. Holbrook N.J. J. Biol. Chem. 2000; 275: 18234-18242Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). Activation of the stress kinase cascade may not be sufficient to induce apoptosis in the cell (17.Xia Z. Dickens M. Raingeaud J. Davis R.J. Greenberg M. Science. 1995; 270: 1326-1331Crossref PubMed Scopus (5036) Google Scholar). In concomitant inactivation of survival signals has been to be a for the kinases to induce cell death (17.Xia Z. Dickens M. Raingeaud J. Davis R.J. Greenberg M. Science. 1995; 270: 1326-1331Crossref PubMed Scopus (5036) Google Scholar, 18.Gupta K. Kshirsagar S. Li W. Gui L. Ramakrishnan S. Gupta P. Law P.Y. Hebbel R.P. Exp. Cell Res. 1999; 247: 495-504Crossref PubMed Scopus (344) Google Scholar, 19.Shan R. Price J.O. Gaarde W.A. Monia B.P. Krantz S.B. Zhao Z.J. Blood. 1999; 12: 4067-4076Crossref Google Scholar, 20.Berra E. Diaz-Meco M.T. Moscat J. J. Biol. Chem. 1998; 273: 10792-10797Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar, 21.Huang Y. Hutter D. Liu Y. Wang X. Sheikh S.M. Chan M.L. Holbrook N.J. J. Biol. Chem. 2000; 275: 18234-18242Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). Thus, the balance between the ERK and the signaling systems critical for enabling the cell to die or survive. the cells control this balance has been The to activation of ERKs and of of signaling of which are by protein may between these and to activity with this inhibition of ERK basal activity in cells has been reported to be sufficient to p38 activation in a H. E. Y. F. M. Mol. Cell. Biol. 1999; 19: PubMed Scopus Google Scholar). It has also been that ERK and may other by on the expression of which on the other S.M. Curr. Opin. Cell Biol. 2000; 12: PubMed Scopus Google Scholar). In the present we show that the PED expression in cells ERK survival function and inhibits apoptotic signaling in 293 Thus, PED expression may a mechanism for the cell to control the balance between ERK and activities and to foster cell survival. recently, PED has been shown to a nuclear sequence (7.Formstecher E. Ramos J.W. Fauquet M. Calderwood D.A. Hseieh J. Canton B. Nguyen X. Barnier J. Camonis J. Ginsberg M. Chneiweiss H. Dev. Cell. 2001; 1: 239-250Abstract Full Text Full Text PDF PubMed Scopus (258) Google Scholar). Through this PED was reported to ERKs to the in (7.Formstecher E. Ramos J.W. Fauquet M. Calderwood D.A. Hseieh J. Canton B. Nguyen X. Barnier J. Camonis J. Ginsberg M. Chneiweiss H. Dev. Cell. 2001; 1: 239-250Abstract Full Text Full Text PDF PubMed Scopus (258) Google Scholar). The cytoplasmic of ERKs not phosphorylation of their substrates, inhibits transcription and cell of cell proliferation also in 293 cells overexpressing PED not Thus, PED is a may the cells to and to of apoptotic are to Dr. E. for the of this also Dr. L. Beguinot di H. S. Milan, for critical of the and Dr. D. for