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1.
It has been previously described by different groups that poly(ADP-ribose) polymerase-1 (PARP-1) and the product of the tumor suppressor gene p53 form tight complexes. We investigated which domains of human PARP-1 and of human wild-type p53 were involved in this protein-protein interaction. We generated baculoviral constructs encoding full length protein or distinct functional domains of both proteins. Baculovirally expressed wild-type p53 was posttranslationally modified. Full length PARP-1 was simultaneously coexpressed in insect cells with full length wt p53 protein or its distinct truncated fragments and vice versa. Reciprocal immunoprecipitation of Sf9 cell lysates revealed that the central and carboxy-terminal fragments of p53 were sufficient to confer binding to PARP-1. The amino-terminal part harboring the transactivation functional domain of p53 was dispensable. On the other hand, the amino-terminal and central fragments of PARP-1 were necessary for complex formation with p53 protein. Finally, we explored the functional significance of the interaction between both proteins. Inactivation of PARP-1 resulted in the reduction of p53 steady-state levels. Inhibition of nuclear export by leptomycin B prevented accelerated degradation of p53 in PARP-1 KO cells and led to accumulation of p53 protein. Considering the fact that the accelerated p53 nuclear export in the absence of PARP-1 contributes to enhanced p53 degradation, we conclude that PARP-1 may mask the NES of p53 through complex formation with its carboxy-terminal part, thereby preventing the export. 相似文献
2.
Schmid G Kramer MP Maurer M Wandl S Wesierska-Gadek J 《Journal of cellular biochemistry》2007,101(6):1355-1369
In recent years, an impact of the p53 tumor suppressor protein in the processes of cellular and organismal ageing became evident. First hints were found in model organisms like Saccharomyces cerevisiae, Caenorhabditis elegans, and Drosophila melanogaster where a clear connection between ageing phenotypes and pathways that are regulated by p53, were found. Interestingly, pathways that are central to the ageing process are usually also involved in energy metabolism and are highly conserved throughout evolution. This also supports the long known empiric finding that caloric restriction has a positive impact on the life span of a wide variety of organisms. Within the last years, on the molecular level, an involvement of the insulin-like growth factor and of the histone deacetylase SRIT1 could be shown. Insight on the impact of p53 on ageing at the organismal level came from mice expressing aberrant forms of the p53 protein. Obviously, the balance of the full length p53 protein and of the shorter p44/DeltaNp53 isomer bear a strong impact on ageing. The shorter isoform regulates full length p53 and in cases where there is too much of the longer isoform, this leads to elevated apoptosis resulting in decreased tumor incidence but also in premature ageing due to exhaustion of the renewal potential. Therefore, modulating the expression of the truncated p53 isoform accordingly, might lead to increased health-span and elevated life-span. 相似文献
3.
We have previously reported that in cells ectopically expressing temperature‐sensitive p53135val mutant, p53 formed tight complexes with poly(ADP‐ribose) polymerase (PARP). At elevated temperatures, p53135val protein, adopting the mutant phenotype, was localized in the cytoplasm and sequestered the endogenous PARP. To prove whether an excess of p53135val protein led to this unusual intracellular distribution of PARP, we have established cell lines overexpressing p53135val + c‐Ha‐ras alone or in combination with PARP. Interestingly, immunostaining revealed that PARP is sequestered in the cytoplasm by mutant p53 in cells overexpressing both proteins. Simultaneous overexpression of PARP had no effect on temperature‐dependent cell proliferation and only negligibly affected the kinetics of p53‐mediated G1 arrest. However, if the cells were completely growth arrested at 32°C and then shifted up to 37°C, coexpressed PARP dramatically delayed the reentry of transformed cells into the cell cycle. Even after 72 h at 37°C the proportion of S‐phase cells was reduced to 20% compared to those expressing only p53135val + c‐Ha‐ras. The coexpressed PARP stabilized wt p53 protein and its enzymatic activity was necessary for stabilization. J. Cell. Biochem. 80:85–103, 2000. © 2000 Wiley‐Liss, Inc. 相似文献
4.
Węsierska-Gądek J Hackl S Zulehner N Maurer M Komina O 《Journal of cellular biochemistry》2011,112(1):273-288
Human MCF-7 breast cancer cells are resistant to pro-apoptotic stimuli due to caspase-3 inactivation. On the other hand, they should be sensitive to agents like selective pharmacological inhibitors of cyclin-dependent kinases (CDKs) that (re)activate p53 tumor suppressor protein because they harbor intact p53 pathways. In this study we examined whether reconstitution of caspase-3 in MCF-7 cells sensitizes them to inhibitors of CDKs, by analyzing the effects of roscovitine (ROSC) and olomoucine (OLO), two closely related selective pharmacological CDK inhibitors, on both mother MCF-7 cells and a secondary mutant line, MCF-7.3.28 that stably expresses human caspase-3. The results show that ROSC is, as expected, much more potent than OLO. Surprisingly; however, ROSC and OLO reduced proliferation of parental MCF-7 cells more strongly than caspase-3-proficient counterparts. Both inhibitors arrest human breast cancer cells at the G(2)-phase of the cell cycle. Analysis of cell-cycle regulators by immunoblotting revealed that ROSC strongly induces p53 protein activity by inducing its phosphorylation at Ser46 in the MCF-7 cells lacking caspase-3, but not in caspase-3-proficient cells. Furthermore, reconstitution of caspase-3 in MCF-7 cells neither elevates the mitochondrial apoptosis rate nor significantly increases caspases activity upon ROSC treatment. However, the stabilization of p53 in response to DNA damaging agents is the same in both caspase negative and positive MCF-7 cells. Cytotoxic agents induce caspase-3-dependent apoptosis in caspase-3-proficient cells. These results indicate that reconstitution of MCF-7 cancer cells with caspase-3 sensitize them to the action of DNA damaging agents but not to ATP-like pharmacological inhibitors of CDKs. 相似文献
5.
UHRF2（ubiquitin like with PHD and ring finger domains 2）是新近发现的具有多个结构域的核蛋白,在细胞周期调控和表观遗传学中发挥重要作用．近期研究提示,UHRF2是肿瘤抑制蛋白p53的1个E3连接酶,在体内外能与p53相互结合并促进其泛素化,过表达UHRF2能使细胞周期停滞于G1期．然而,UHRF2介导的G1期阻滞及其与p53联系尚不清楚．通过共转染UHRF2质粒及p53特异性小干扰RNA(siRNAs)到HEK293细胞构建细胞模型,探索UHRF2引起细胞周期停滞与p53之间的关系．结果显示,UHRF2能促进HEK293细胞中p53的稳定,从而引起p21 (CIP1/WAF1)基因表达,并使细胞周期停滞于G1期;但在siRNA抑制p53的表达后p21(CIP1/WAF1)表达降低,UHRF2引起的细胞周期阻滞消除．研究结果提示,UHRF2可通过稳定p53,上调p21的表达,从而介导细胞周期阻滞于G1期;同时UHRF2可能参与细胞周期调控及DNA损伤反应（DNA damage response, DDR）．UHRF2稳定p53的具体分子机制及其在DDR中的作用有待进一步研究证明． 相似文献
6.
We reported recently that roscovitine (ROSC), a selective cyclin-dependent kinase (CDK) inhibitor, arrests human MCF-7 breast cancer cells in G(2) phase of the cell cycle, and concomitantly induces apoptosis. Human MCF-7 breast cancer cells are known to express elevated levels of c-Ha-Ras protein. To achieve full biological activity, de novo synthesized c-Ha-Ras protein has to be farnesylated and after further processing it needs to be attached to the plasma membrane. Therefore, we decided to prove whether prevention of protein farnesylation would sensitize MCF-7 cells to the action of ROSC. MCF-7 cells were treated with 1-40 microM ROSC alone, or in combination with L-744,832, an inhibitor of farnesyl protein transferase (FTPase). To measure the impact on the proliferation of the cells, we used the CellTiterGlo viability assay and FACS analysis was employed to quantify the DNA-content of the single cells. The amount and phosphorylation status of relevant proteins after lysis of MCF-7 cells was assessed on Western blots using (phospho)-specific antibodies. The combined treatment with L-744,832 and ROSC for 24 h, markedly reduced the number of viable MCF-7 cells, primarily, by re-enforcing the cell cycle arrest. Interestingly, the potentiation of the ROSC-mediated inhibition of cell proliferation became evident during the 48 h post-incubation period in presence of the FPTase inhibitor. Inhibition of FPTase in ROSC-treated cells reduced the number of viable cells by approximately 30%. Evidently, the combined treatment sensitizes MCF-7 cells to the action of ROSC, thereby allowing to reduce the dose of the drug and to minimize side effects. 相似文献
7.
Human MCF-7 breast cancer cells are relatively resistant to conventional chemotherapy due to the lack of caspase-3 activity. We reported recently that roscovitine (ROSC), a potent cyclin-dependent kinase 2 inhibitor, arrests human MCF-7 breast cancer cells in the G(2) phase of the cell cycle and concomitantly induces apoptosis. Exposure of MCF-7 cells to ROSC also strongly activates the wt p53 tumor suppressor protein in a time- and dose-dependent manner. The p53 level increased despite upregulation of Hdm-2 protein and was attributable to the site-specific phosphorylation at Ser-46. The p53 protein phosphorylated at serine 46 causes the up-regulation of the p53AIP1 protein, a component of mitochondria. In the present study we identified the pathway mediating ROSC-induced p53 activation. Exposure of MCF-7 cells to ROSC activated homeodomain-intereacting protein kinase-2 (HIPK2). The overexpression of wild-type but not kinase inactive HIPK2 increased the basal and ROSC-induced level of p53 phosphorylation at Ser-46 and strongly enhanced the rate of apoptosis in cells exposed to ROSC. We show that HIPK2 is activated by ROSC and mediates ROSC-induced P-Ser-46-p53, thereby stabilizing wt p53 and increasing the efficacy of drug-induced apoptosis in MCF-7 cells. These results identify HIPK2 as a component of the ROSC-induced signaling pathway leading to the stabilization and activation of wt p53 protein. 相似文献
8.
Wesierska-Gadek J Schreiner T Gueorguieva M Ranftler C 《Journal of cellular biochemistry》2006,98(6):1367-1379
We reported recently that roscovitine (ROSC), a selective cyclin-dependent kinase (CDK) inhibitor, arrested human MCF-7 breast cancer cells in G2 phase of the cell cycle and concomitantly induced apoptosis. On the other hand, ROSC-induced G1 arrest observed by another group has not been accompanied by apoptosis. Therefore, we decided to prove to which extent components of tissue culture media could affect the primary action of ROSC. For this purpose we compared the efficacy of the ROSC treatment on MCF-7 cells cultivated in medium with and without phenol red. The kinetics of MCF-7 cell proliferation strongly depended on the presence of phenol red that has been recognized previously as a weak estrogen. Exposure of MCF-7 cells cultivated in phenol red-deprived medium to ROSC resulted in a strong G2 arrest and apoptosis. However, the anti-proliferative and pro-apoptotic action of ROSC was strongly diminished in cells maintained in medium containing phenol red. The ratio of the G2 cell population after 12 h ROSC was reduced by approximately 20% in the latter and correlated with the lack of CDK2 inactivation. Moreover, the kinetics of ROSC-induced apoptosis was delayed in the presence of phenol red. These results clearly evidence that the efficacy of the therapy of ER-positive breast cancers by CDK inhibitors is diminished in the presence of estrogen-mimicking compounds and indicate that phytoestrogens and xenoestrogens could interfere with the therapy. Therefore, the exposure of cancer patients to the estrogen mimics should be avoided at least during chemotherapy by CDK inhibitors. 相似文献
9.
Transport of proteins between cytoplasm and nucleus is mediated by transport factors of the importin α- and β-families and occurs along a gradient of the small GTPase Ran. To date, in vivo analysis as well as prediction of protein nuclear export remain tedious and difficult. We generated a novel bipartite assay called NEX-TRAP (Nuclear EXport Trapped by RAPamycin) for in vivo analysis of protein nuclear export. The assay is based on the rapamycin-induced dimerization of the modules FRB (FK506-rapamycin (FR)-binding domain) and FKBP (FK506-binding protein-12): a potential nuclear export cargo is fused to FRB, to EYFP for direct visualization as well as to an SV40-derived nuclear localization signal (NLS) for constitutive nuclear import. An integral membrane protein that resides at the trans Golgi network (TGN) is fused to a cytoplasmically exposed FKBP and serves as reporter. EYFP-NLS-FRB fusion proteins with export activity accumulate in the nucleus at steady state but continuously shuttle between nucleus and cytoplasm. Rapamycin-induced dimerization of FRB and FKBP at the TGN traps the shuttling protein outside of the nucleus, making nuclear export permanent. Using several example cargoes, we show that the NEX-TRAP is superior to existing assays owing to its ease of use, its sensitivity and accuracy. Analysis of large numbers of export cargoes is facilitated by recombinational cloning. The NEX-TRAP holds the promise of applicability in automated fluorescence imaging for systematic analysis of nuclear export, thereby improving in silico prediction of nuclear export sequences. 相似文献
10.
Gregory R. Kardos Mu‐Shui Dai Gavin P. Robertson 《Pigment cell & melanoma research》2014,27(5):801-812
Ribosome biogenesis can modulate protein synthesis, a process heavily relied upon for cancer cell proliferation. In this study, involvement of large subunit ribosomal proteins (RPLs) in melanoma has been dissected and RPLs categorized based on modulation of cell proliferation and therapeutic targeting potential. Based on these results, two categories of RPLs were identified: the first causing negligible effects on cell viability, p53 expression, and protein translation, while the second category decreased cell viability and inhibited protein synthesis mediated with or without p53 protein stabilization. RPL13 represents the second category, where siRNA‐mediated targeting inhibited tumor development through decreased cellular proliferation. Mechanistically, decreased RPL13 levels increased p53 stability mediated by RPL5 and RPL11 binding to and preventing MDM2 from targeting p53 for degradation. The consequence was p53‐dependent cell cycle arrest and decreased protein translation. Thus, targeting certain category 2 RPL proteins can inhibit melanoma tumor development mediated through the MDM2‐p53 pathway. 相似文献
11.
JNK1/2 proteins belong to the family of stress-activated protein kinases. They play a complex role in growth regulation, inducing either cell death or growth support. In this report, we provide evidence that, in human melanoma cells, JNK inhibition with the small molecule inhibitor SP600125 induces either predominantly a G2/M arrest or apoptosis depending on the cell line. In 1205Lu cells, JNK inhibition induced cell cycle arrest through p53-dependent induction of p21 Cip1/Waf1 expression, while in WM983B cells, induction of apoptosis by JNK inhibition was accompanied by p53, Bad and Bax induction, not p21 Cip1/Waf1. JNK inhibition with the small molecule inhibitor SP600125 slowed growth of all cell lines, although the effect was markedly greater in cells exhibiting high phospho- (P-)JNK1 levels. Specific gene knockdown of JNK1 by means of siRNA oligonucleotides inhibited cell growth only in melanoma cell lines exhibiting high P-JNK1 levels. siRNAs directed against JNK2 did not reduce cell growth in any of the cell lines tested. Together, our findings demonstrate that JNK, and in particular the JNK1 isoform, support the growth of melanoma cells, by controlling either cell cycle progression or apoptosis depending on the cellular context. 相似文献
12.
13.
《Cell cycle (Georgetown, Tex.)》2013,12(7):1393-1399
Kaposi sarcoma (KS) tumors often contain a wild-type p53. However, the function of this tumor suppressor in KS tumor cells is inhibited by both MDM2 and latent nuclear antigen (LANA) of Kaposi sarcoma-associated herpes virus (KSHV). Here, we report that MDM2 antagonist Nutlin-3 efficiently reactivates p53 in telomerase-immortalized human umbilical vein endothelial cells (TIVE) that had been malignantly transformed by KSHV as well as in KS tumor cells. Reactivation of p53 results in a G1 cell cycle arrest, leading to inhibition of proliferation and apoptosis. Nutlin-3 inhibits the growth of “KS-like” tumors resulting from xenografted TIVE-KSHV cells in nude mice. In addition, Nutlin-3 strongly inhibits expression of the pro-angiogenic and pro-inflammatory cytokine angiopoietin-2 (Ang-2). It also disrupts viral latency by inducing expression of KSHV lytic genes. These results suggest that Nutlin-3 might serve as a novel therapy for KS. 相似文献
14.
Wesierska-Gadek J 《Journal of cellular biochemistry》2005,95(5):1012-1028
Inactivation of poly(ADP-ribose) polymerase-1 (PARP-1) has been shown to potentiate the cytotoxicity of distinct DNA targeting agents including topoisomerase I inhibitors. On the other hand, the PARP-1 deficient cells exhibited resistance to conventional inhibitors of topoisomerase II such as etoposide or doxorubicin (DOX). Recently, we observed the extreme sensitivity of PARP-1 knock-out (KO) cells to C-1305, a new biologically active triazoloacridone compound. C-1305 permanently arrested the cells in G2-phase of the cell-cycle. These observations prompted us to investigate more thoroughly the susceptibility of PARP-1 KO cells to DOX and to examine the effect of DOX on the progression of cell-cycle. We determined the uptake of DOX and P-glycoprotein (P-gp) expression in mouse cells and compared it with that in human myeloma 8226/Dox40 cells overexpressing P-gp. Exposure of mouse cells to DOX revealed a reduced drug uptake in cells lacking PARP-1. However, combined treatment with verapamil, a potent MDR modulator increased the DOX accumulation. Detailed immunoblotting experiments revealed an approximately threefold higher P-gp level in PARP-1 KO cells as compared with normal counterparts. Interestingly, DOX induced in normal fibroblasts very rapidly G2 arrest whereas in PARP-1 KO cells it blocked primarily the transition between S and G2 resulting in the increase of cells remaining in S-phase. This coincided with the lack of the site-specific phosphorylation of CDK2. Simultaneous inhibition of P-gp in cells lacking PARP-1 resulted in an accumulation of cells in G2. Exposure of mouse cells to high DOX dose activated significantly caspase-3/7 in PARP-1 KO cells. 相似文献
15.
Wild-type p53 accumulates in the nucleus following stress. Current models suggest this nuclear accumulation involves phosphorylation at p53 N-terminal sites, and inhibition of murine double minute (MDM)2-dependent nuclear export. We monitored the effects of stress on MDM2-dependent nuclear export of wild-type p53 and a mutant lacking N-terminal phosphorylation sites. Etoposide and ionizing radiation inhibited nuclear export of wild-type p53 and the phosphor-mutant to comparable extents, indicating nuclear export inhibition does not require N-terminal phosphorylation. Cytoplasmic p53 accumulated in the nucleus of transfected cells treated with the nuclear export-inhibitor leptomycin B (LMB). Interestingly, LMB caused less p53 nuclear accumulation than stress treatment, suggesting stress-induced nuclear accumulation of p53 does not result solely from inhibited nuclear export. 相似文献
16.
Penta-acetyl geniposide, (Ac)(5)-GP, was produced by acetylation of a glycoside, isolated from an extract of Gardenia fructus. Previously, we have reported that C6 glioma cells could be inhibited in culturing as well as in bearing rats by treating with (Ac)(5)-GP. In this study, the effect and action of (Ac)(5)-GP on inducing cell death was examined in rat C6 glioma cells. Treatment of C6 glioma cells with (Ac)(5)-GP caused cell death, chromatin condensation, and internucleosomal DNA ladder. Also, cell cycle arrest at G(0)/G(1) phase revealed that (Ac)(5)-GP-induced cell death appears to be mediated by apoptosis. In addition, the results also showed that p53 and c-Myc increased due to treatment of (Ac)(5)-GP in a dose-response and time-dependent manner. Concomitant with the expression of p53 and c-Myc, decreased level of Bcl-2 and increased level of Bax protein were observed. These results suggest that cell death caused by (Ac)(5)-GP through apoptosis and cell cycle arrest at G(0)/G(1) may be associated with the induction of p53, c-Myc and may be mediated with apoptosis-related Bcl-2 family proteins. 相似文献
17.
Ras, the product of a proto-oncogene, is a GTP-hydrolyzing enzyme found mutated in approximately 50% of human cancers. \"Gain of function\" mutations of Ras lead to an escape of transformed cells from cell-cycle control, rendering them independent to stimulation by growth factors, giving them almost unlimited proliferation capacity. The cytosolic precursor isoform of Ras is biologically inactive. After several post-translational modifications, Ras is anchored to the plasma membrane and, thereby, the protein becomes activated. The finding that lipid modifications of Ras protein, particularly farnesylation, are essential for its signal transduction activity, gave rise to the concept that blocking farnesyl protein transferase (FPTase), the enzyme catalyzing the first step in the Ras modification cascade, would prevent proper membrane anchoring and provide an improved approach in the cure of tumors harboring Ras mutations. In the present study we used transformed rat cells overexpressing a temperature-sensitive p53 protein, adopting wt conformation at 32 degrees C and mutant conformation at 37 degrees C. We treated the cells growing at 32 or 37 degrees C with doxorubicin alone, or in combination with inhibitors of FPTase. Combined treatment was more efficient and the same inhibition of cell proliferation was reached at lower DOX concentrations. The treatment strongly affected the growth rate of tumor cells but only negligibly of normal cells. However, the inhibitors of FPTase prevented the membrane anchoring in both situations. These results show two striking advantages of the combined treatment: the desired cytostatic effect on tumor cells at lower drug concentrations and clearly reduced adverse effects on quiescent cells. 相似文献
18.
Tumor suppressor p53 is an essential regulator in mammalian cellular responses to DNA damage including cell cycle arrest and apoptosis. Our study with Chinese hamster ovary CHO-K1 cells indicates that when p53 expression and its transactivation capacity was inhibited by siRNA, UVC-induced G2/M arrest or apoptosis were unaffected as revealed by flow cyotmetric analyses and other measurements. However, inhibition of p53 rendered the cells slower to repair UV-induced damages upon a plasmid as shown in host cell reactivation assay. Furthermore, the nuclear extract (NE) of p53 siRNA-treated cells was inactive to excise the UV-induced DNA adducts as analyzed by comet assay. Consistently, the immunodepletion of p53 also deprived the excision activity of the NE in the similar experiment. Thus, tumor suppressor p53 of CHO-K1 cells may facilitate removal of UV-induced DNA damages partly via its involvement in the repair mechanism. 相似文献
19.
Wesierska-Gadek J Wandl S Kramer MP Pickem C Krystof V Hajek SB 《Journal of cellular biochemistry》2008,105(5):1161-1171
Exposure of human HeLaS(3) cervix carcinoma cells to high doses of conventional cytostatic drugs, e.g. cisplatin (CP) strongly inhibits their proliferation. However, most cytostatic agents are genotoxic and may generate a secondary malignancy. Therefore, therapeutic strategy using alternative, not cytotoxic drugs would be beneficial. Inhibition of cyclin-dependent kinases (CDKs) by pharmacological inhibitors became recently a promising therapeutic option. Roscovitine (ROSC), a selective CDK inhibitor, efficiently targets human malignant cells. ROSC induces cell cycle arrest and apoptosis in human MCF-7 breast cancer cells. ROSC also activates p53 protein. Activation of p53 tumor suppressor protein is essential for induction of apoptosis in MCF-7 cells. Considering the fact that in HeLaS(3) cells wt p53 is inactivated by the action of HPV-encoded E6 oncoprotein, we addressed the question whether ROSC would be able to reactivate p53 protein in them. Their exposure to ROSC for 24 h induced cell cycle arrest at G(2)/M and reduced the number of viable cells. Unlike CP, ROSC in the used doses did not induce DNA damage and was not directly cytotoxic. Despite lack of detectable DNA lesions, ROSC activated wt p53 protein. The increase of p53 levels was attributable to the ROSC-mediated protein stabilization. Further analyses revealed that ROSC induced site-specific phosphorylation of p53 protein at Ser46. After longer exposure, ROSC induced apoptosis in HeLaS(3) cells. These results indicate that therapy of HeLaS(3) cells by ROSC could offer an advantage over that by CP due to its increased selectivity and markedly reduced risk of generation of a secondary cancer. 相似文献
20.
Tatyana S. Nekova Susanne Kneitz Hermann Einsele Ralf Bargou Gernot Stuhler 《Cell cycle (Georgetown, Tex.)》2016,15(23):3203-3209
Small molecule inhibitors targeting CDK1/CDK2 have been clinically proven effective against a variety of tumors, albeit at the cost of profound off target toxicities. To separate potential therapeutic from toxic effects, we selectively knocked down CDK1 or CDK2 in p53 mutated HACAT cells by siRNA silencing. Using dynamic, cell cycle wide proteome arrays, we observed minor changes in overall abundance of proteins critically involved in cell cycle transition despite profound G2/M or G1/S arrest, respectively. Employing phospho site specific analyses, we identified uncoupled mitogenic, yet pro-apoptotic signaling from counter balancing anti-apoptotic activity in CDK2 disrupted cells. Moreover, a crucial role of CDK2 activity in early serum response was observed, extending well-established roles of CDKs outside their cell cycle regulating functions. In contrast, disruption of CDK1 only marginally affected phosphorylation events of crucial signaling nodes prior to G2/S transition. The data presented here suggest that the temporal separation of pro- and anti-apoptotic pathways by selective inhibition of CDK2 disrupts coherent signaling modules and may synergize with anti-proliferative drugs, averting toxic side effects from CDK1 inhibition. 相似文献