p53 in life and death.

Introduction One of the supreme challenges faced in cancer therapy is the small therapeutic window afforded by chemotherapeutic agents and radiation therapy. Many of these agents act by damaging DNA. This DNA damage is believed to be directly lethal to rapidly growing cancer cells but also produces toxicity through effects on normal cells. A major therapeutic research goal in molecular oncology is to identify factors and pathways with unique roles in tumor cells, potentially providing explanations for therapeutic successes and targets for new drug discovery. There has been an accumulation of data in recent years indicating that the DNA damage induced by chemotherapy or radiation may function in certain contexts as a signal to trigger apoptosis, a characteristic and orderly suicide program inherent to the cell. A number of genes have been identified as regulators of this process. One such gene, p53, also has emerged as one of the most commonly aberrant tumor suppressor genes in human cancers. The roles ofp53 in tumorigenesis and cell death and the potential implications of these activities are explored in this review.