EP300 and prostate cancer: Replicating mutants that are defective in binding to p300/CBP (dl1101, dl1104), p400/p21 (dl1101, dl1102), pRb, p130 and p170 (dl922–947, dl1108), or pRb and p130 (dl1107) [35], [36], [37], [38], were evaluated for cytotoxicity in human prostate cancer cells (Fig. 1A).