CRISPR/Cas9 KO of PALB2, RAD51B, RAD51C, RAD54L, or ATM sensitises cell models to olaparib treatment. Dose–response curves for SKOV3 (A) and DU145 (B) isogenic pairs treated with olaparib for 10–14 days in clonogenic survival assays. Results are shown as mean of n = 4 biological replicates ± SD. Quantification of RAD51 and γH2AX foci by immunofluorescence in SKOV3 (C) and DU145 (D) isogenic pairs 4 hours after treatment with 5 Gy of ionizing radiation or in untreated cells. Results are shown as mean number of foci per nucleus in replicating (EdU-positive) cells (n = 3 biological replicates ± SD). Dose–response curves for DU145 (E) and SKOV3 (F) isogenic pairs treated with olaparib for 10–14 days in clonogenic survival assays. Results are shown as mean of n = 4 biological replicates ± SD for the dose–response curves. Curves for WT, BRCA1 KO DU145, and BRCA2 KO SKOV3 are the same as the ones shown in Fig. 1.