TP53 and breast cancer: Although ING3 was previously reported to activate the p53-responsive gene CDKN1A using a transient luciferase reporter assays in colon carcinoma cells (Nagashima et al, 2003; Doyon et al, 2006), we observed that silencing of ING3 induced the expression of CDKN1A in breast cancer and PC cells (Figure 4B), whereas exogenous expression of ING3 driven by a doxycycline-inducible system repressed the expression of CDKN1A (Figures 7F and I).