Knockout mice for p53−/−, p73−/− and p63−/− highlight the major physiological roles of these proteins (96), suggesting pivotal functions in the development of nervous and immune systems (mediated by p73), in skin and limb development (mediated by p63) and in tumor suppression (mediated primarily by p53) (111, 145–148). This evidence concerns the gene TP73 and neoplasm.