Several recent observations have shown that p53 knockout mice, lacking p21, p53 upregulated modulator of apoptosis (Puma), and Noxa (Latin for damage, also known as phorbol-12-myristate-13-acetate-induced protein PMAIP1; sensitizer of BH3) are not susceptible to tumor development, suggesting that p53 not only can suppress a tumor but also can control numerous cellular processes that substantially contribute to the suppression of cancer cell proliferation [55]. This evidence concerns the gene PMAIP1 and cancer.