TP53 and cancer: Indeed, several lines of evidence, including the promotion of induced pluripotent stem cells by silencing p53 (Guo et al., 2014), and the spontaneous formation of tetraploid cells, as proposed cancer precursor cells, in p53 knockout mice (Livingstone et al., 1992; Harvey et al., 1993), suggest that low levels of p53 are required for housekeeping and homeostasis functions in cells.