APA Dictionary of Psychology

n. a tumor-suppressor gene that regulates an organism’s cell cycle and protects the cell’s DNA from damage. Mutations in p53 cause cells to become malignant. Germ-line mutations in p53 are responsible for most cases of Li–Fraumeni syndrome, and in families with this syndrome, carriers of p53 mutations have a 90% lifetime risk of developing one or more kinds of cancer.