Dictionary of Human Evolution and Biology

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P53 Tumor Suppressor (protein)

A protein with a molecular mass of 53 kilodaltons; normally restrains the proliferation of cells, and is involved in 60% of all cancer types, but especially cervical and colon cancers. Wild type p53 normally functions as a tumor suppressor or cancer killer, by proliferating rapidly in the presence of a nascent tumor. p53 normally activates cell growth inhibitors, resulting in apoptosis; it suppresses DNA transcription until polymerase enzymes can repair DNA damaged by carcinogens. Mutations in p53 can cause cessation of these functions, leading to familial cancers. Most p53 mutations are new (de novo) somatic mutations. About 35 allelic mutations have been described, each associated with a specific cancer or variant. The unmutated p53 tumor suppressor is a candidate for gene therapy. The p53R2 gene may mediate the effects of the p53 tumor suppressor gene.

Cf. ras oncogene.

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