p53 : The p53 Gene is a tumor suppressor gene. If a person inherits only one functional copy of the p53 gene from their parents, they are predisposed to cancer and usually develop several independent tumors in a variety of tissues in early adulthood. This condition is rare, and is known as Li-Fraumeni syndrome. Li Fraumeni syndrome predisposes patients to breast cancer and sarcoma. p53 is also a transcription factor and is not found only in malignant cells. It has a role in downregulating cell division and apoptosis.