Lastly, the triple knockout mice that are deleted for p21, p53-upregulated modulator of apoptosis (PUMA) and phorbol-12-myristate-13-acetate-induced protein 1 (NOXA/PMAIP1), which are important p53 target genes for inducing cell cycle arrest (p21) and apoptosis (PUMA and NOXA), are not more tumor-prone than wild-type mice [3]. Here, TP53 is linked to neoplasm.