p53 (aka TP53) is one of the most intensively studied proteins encoded in the human genome, and presently there are over 64,000 scientific papers dealing with various aspects of its function. Initially thought to promote cancer and later to suppress cancer, our understating of p53 has dramatically changed over the past thirty years. p53 is now known to regulate several hundred different genes and gene products and be involved in an enormous number of different functions, including cancer suppression and the regulation of cell division, aging, cell death, responses to hypoxia, embryo implantation, DNA repair, mitochondrial function, cellular anti-oxidant defenses, and promoting aerobic metabolism and exercise tolerance. Over the last ten years transgenic animals carrying extra p53 copies have shown a high resistance to developing cancer, and drugs that activate p53 in tumor cells have shown promise as anti-cancer therapies.
Since p53 is mutated in over 50% of human cancers, a successful anti-cancer therapy targeting p53 could have wide applications to many differ type of cancer. Therefore p53 is a likely candidate for the first genetic alterations performed on humans to lower individual disease risk.