- P21
Cyclin-dependent kinase inhibitor 1A (p21, Cip1), also known as CDKN1A, is a human
gene .PBB_Summary
section_title =
summary_text = This gene encodes a potent cyclin-dependent kinase inhibitor. The encoded protein binds to and inhibits the activity of cyclin-CDK2 or -CDK4 complexes, and thus functions as a regulator of cell cycle progression at G1. The expression of this gene is tightly controlled by the tumor suppressor protein p53, through which this protein mediates the p53-dependent cell cycle G1 phase arrest in response to a variety of stress stimuli. This protein can interact with proliferating cell nuclear antigen (PCNA), a DNA polymerase accessory factor, and plays a regulatory role in S phase DNA replication and DNA damage repair. This protein was reported to be specifically cleaved by CASP3-like caspases, which thus leads to a dramatic activation of CDK2, and may be instrumental in the execution of apoptosis following caspase activation. Two alternatively spliced variants, which encode an identical protein, have been reported. [cite web | title = Entrez Gene: CDKN1A cyclin-dependent kinase inhibitor 1A (p21, Cip1)| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=1026| accessdate = ]p21, also known as cyclin-dependent kinase inhibitor 1A or CDKN1A, is a human gene on
chromosome 6 (location 6p21.2), that encodes acyclin -dependentkinase inhibitor that directly inhibits the activity ofcyclin-CDK2 andcyclin-CDK4 complexes. p21 functions as a regulator ofcell cycle progression atS phase A. L. Gartel and S. K. Radhakrishnan (2005) "Lost in transcription: p21 repression, mechanisms, and consequences" in "Cancer Research" Volume 65, pages 3980-3985. Entrez Pubmed|15899785] . The expression of p21 is controlled by the tumor suppressor proteinp53 .The function of this gene relates in part to stress response R. Rodriguez and M. Meuth. (2006) "Chk1 and p21 cooperate to prevent apoptosis during DNA replication fork stress" in "Molecular Biology of the Cell" Volume 17, pages 402-412. Entrez Pubmed|16280359] . p21 is the major transcriptional target of the tumor suppressor gene, p53; despite this, loss-of-function mutations in p21 (unlike p53) do not accumulate in cancer nor do they predispose to cancer incidence. In fact, mice genetically engineered to lack p21, develop rather normally and are not susceptible to cancer (again, unlike p53).
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