TP53 and cancer: We found that p53 binding at identified sites in RPE1 cells in response to IR was highly correlated with p53 binding in the 12 cancer cell lines (Fig. 1d; average Pearson r = 0.48+/− 0.117 for correlation (RPE, Cancer Lines) vs an average of 0.53+/− 0.099 for correlation (Cancer, Cancer)).