The p53 gene has a key role in the cell cycle control. When mutated, it promotes the development of neoplasms, acting in so far as a tumor suppressor gene in normal conditions. Recently, genes homologue to p53 were identified, named p73 e p63, probably originated from a common ancestral gene. Despite the great structural homology, the members of p53 family have functional differences. This article aims to discourse about the major structural and functional aspects of p73 and p63, reinforcing their role in human tumorigenesis. P73 activates several p53 responsive genes and, when overexpressed, inhibits the p53 action. It is rarely mutated in neoplasms and its role in human tumorigenesis is still controversial. P63 is not a classical tumor suppressor gene, being essential for the maintenance of a population of precursor cells (stem cells) in several epithelial tissues. P63 is detectable in the basal cells of several epithelial organs like skin and prostate and could be considered a hallmark of cellular undifferentiation. P63 is a recently described marker and still requires more investigations to determine its role in the development of neoplasms in humans.
p53; p73; p63; Apoptosis; Cell cycle; Neoplasia
