p53

The p53 tumor suppressor gene is the most frequently mutated gene in human cancer. P53 protein is present in the nucleus of almost all normal cells, but it is usually not immunohistochemically detectable due to a very short half-life. Mutated p53 shows impaired DNA-binding and release from cell cycle checkpoint control following DNA damage, thereby increasing genomic instability and promoting gene amplification. Mutated p53 has a prolonged half-life and can be detected by immunohistochemistry.