[Role of the p53 gene in apoptosis]

Cell numbers are controlled by a homeostatic mechanism between cell growth, arrest and programmed cell death (apoptosis) in normal and cancerous tissues. One of the tumor suppressor genes, p53, functions as a transcription factor or transcriptional regulator through DNA and protein binding properties, and plays an important role in regulating cell cycle and induction of apoptosis. Although there are two apoptotic pathways, p53-independent and p53-dependent, the latter will be emphasized and discussed in this section. Since p53 is often inactivated due to mutation in human cancers, understanding the p53-dependent apoptotic pathway is extremely important. Analysis of p53-dependent apoptosis as well as apoptosis caused by other p53-related genes should provide a clue to a new strategy for cancer therapy.