We measured CX5461 drug sensitivity in isogenic BRCA2−/− and WT colorectal cancer DLD1 cells; BRCA2 deficient ovarian cancer cell line PEO1 vs the BRCA2 proficient C4-2 (ref. 22); and BRCA2 proficient and knockout breast tumour cells derived from p53 knockout mouse (BRCA2−/−; p53−/− (KB2P 1.21) vs BRCA2+/+; p53−/− (KP6.3) cells)23. The gene discussed is TP53; the disease is colorectal cancer.