Fig. 4. Role of mutant p53 binding to p73. Both p53 and p73 can induce apoptosis and growth arrest. Some of the stress signals that activate p53 and p73 are depicted in this figure. p53 mutation is common in human cancers. Certain p53 mutant proteins bind to p53 and inhibit p53-dependent transactivation and apoptosis. In addition, a subset of p53 mutant proteins can also bind to and inhibit p73-dependent activities. The interaction between mutant p53 and p73 is enhanced when the p53 codon 72 polymorphism encodes an Arg rather than a Pro (bold line).