ID8 cells, obtained from Dr Katherine Roby (University of Kansas Medical Center, KS), were cultured in DMEM supplemented with 4% fetal calf serum, 100µg/ml penicillin, 100µg/ml streptomycin and ITS (5 µg/ml insulin, 5µg/ml transferrin and 5ng/ml sodium selenite). As ID8 was obtained directly from their original source, separate STR validation was not performed. For cytotoxicity assays, cells were plated onto 24 plates (3x103 cells/well) in triplicate. Survival was assessed by MTT assay (Nutlin-3) or sulphorhodamine B assay (rucaparib) after 72 hours.