The absence of effect of Atm on p53-dependent tumor suppression is in sharp contrast with a number of reports where the absence of Arf essentially eliminates p53-mediated tumor suppression and completely alleviates the selective pressure to inactivate p53 in lymphomas, sarcomas and skin tumors [26]–[28], [48], [49]. The gene discussed is CDKN2A; the disease is neoplasm.