TP53 and neoplasm: On the basis of our results we propose a model of inhibition of mammary carcinogenesis by DHEA that involves the suppression of cell proliferation, the induction of senescence in tumor cells and the induction of apoptosis (Fig. 5); these cellular events are apparently associated with the upregulation of p16 and p21 but not that of p53, implying a p53-independent mechanism.