TP53 and cancer: Collectively, these results suggest a model in which gain-of-function mutant p53 protein acts aberrantly, at least, at two different regulation levels to maintain genomic instability in cancer cells; it is able to transcriptionally inhibit BRCA1 and RAD17 gene expression [9] and to induce miR-205-5p [20] that targets BRCA1 and RAD17 (Figure 6I).