The p21 encoded protein binds to and inhibits the activity of Cyclin-CDK2 or -CDK4 complexes and functions as a regulator of cell cycle progression at G1. The expression of the p21 antibody gene is controlled by the tumor suppressor p53, through which this protein mediates the p53-dependent cell cycle arrest in response to a variety of stress stimuli. Studies have shown that the re-localization of 21WAFI/CIPI from the nucleus to the cytoplasm, results in a loss of those tumor suppressor functions. This loss has shown to be a negative prognostic factor in breast cancers, renal carcinoma, gastric and colon cancer.
1. Winters ZE, Hunt NC, Bradburn MJ, Royds JA, Turley H, Harris AL, Norbury CJ: Subcellular localization of cyclin B, Cdc2 and p21WAF1/CIPI in breast cancer: association with prognosis. Eur J Cancer 2001, 37:2405-2412.
2. Zhou BP, Liao Y, Xia W, Spohn B, Lee M-H, Hung M-C: Cytoplasmic localisation of p21Cip1/WAF1 by Akt-induced phosphorylation in HER-2/neu-overexpressing cells. Nat Cell Biol 2001, 3:245-252.
3. Winters ZE, Leek RD, Bradburn MJ, Norbury CJ, Harris AL. Cytoplasmic p21WAF1/CIP1 expression is correlated with HER-2/ neu in breast cancer and is an independent predictor of prognosis. Breast Cancer Res. 2003;5(6):R242-9. Epub 2003 Oct 3.
4. Center for Disease Control Manual. Guide: Safety Management, NO. CDC-22, Atlanta, GA. April 30, 1976 “Decontamination of Laboratory Sink Drains to Remove Azide Salts.”
5. National Committee for Clinical Laboratory Standards(NCCLS). Protection of laboratory workers from infectious diseases transmitted by blood and tissue; proposed guideline. Villanova, PA 1991;7(9). Order code M29-P.