Description
Protocol
Available protocols: ELISA+
Specificity / Sensitivity
PathScan
Species Reactivity: Human
Background
The tumor suppressor protein p21 Waf1/Cip1 acts as an inhibitor of cell cycle progression. It functions in stoichiometric relationships forming heterotrimeric complexes with cyclins and cyclin-dependent kinases. In association with CDK2 complexes, it serves to inhibit kinase activity and block progression through G1/S (1). However, p21 may also enhance assembly and activity in complexes of CDK4 or CDK6 and cyclin D (2). The carboxy-terminal region of p21 is sufficient to bind and inhibit PCNA, a subunit of DNA polymerase, and may coordinate DNA replication with cell cycle progression (3). Upon UV damage or during cell cycle stages when cdc2/cyclin B or CDK2/cyclin A are active, p53 is phosphorylated and upregulates p21 transcription via a p53-responsive element (4). Protein levels of p21 are downregulated through ubiquitination and proteasomal degradation (5).
Alternate Names
CAP20; CDK-interacting protein 1; CDK-interaction protein 1; CDKN1; CDKN1A; CDN1A; CIP1; cyclin dependent kinase inhibitor 1A; Cyclin-dependent kinase inhibitor 1; cyclin-dependent kinase inhibitor 1A (p21, Cip1); DNA synthesis inhibitor; MDA-6; MDA6; melanoma differentiation associated protein 6; Melanoma differentiation-associated protein 6; p21; p21CIP1; p21Cip1/Waf1; PIC1; SDI1; WAF1; wild-type p53-activated fragment 1
