Traditionally, the p21 protein has been defined as an inhibitor of cyclin-dependent kinases (CDKs). Inhibition of this group of enzymes by p21 leads to the cessation of cell proliferation. Additionally, p21 binds to and inhibits the activity of PCNA (proliferating cell nuclear antigen, a subunit of DNA polymerase), which results in the termination of DNA replication. Because both of these functions lead to cell cycle arrest, p21 is also called an inhibitor of the cell cycle.
KeywordsActin Stress Fiber Formation Adenomatosis Polyposis Coli Cyclin Subunit Proliferation Inhibitory Signaling
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