CDKN2A

CDKN2A, also known as cyclin-dependent kinase Inhibitor 2A, is a gene which in humans is located at chromosome 9, band 21.3. The gene codes for two proteins, including p16 (or p16INK4a) and p14arf. Both act as tumor suppressors by regulating the cell cycle. p16 inhibits cyclin dependent kinases 4 and 6 (CDK4 and CDK6) and thereby activates the retinoblastoma (Rb) family of proteins, which block traversal from G1 to S-phase. p14ARF (also known as p19ARF in the mouse) activates the p53 tumor suppressor. Somatic mutations of CDKN2A are common in the majority of human cancers, with estimates that CDKN2a is the second most commonly inactivated gene in cancer after p53. Germline mutations of CDKN2a are associated with familial melanoma, glioblastoma and pancreatic cancer.