NHEJ was assessed in a panel of ovarian cancer cell lines and 47 primary ascitic derived ovarian cancer cultures, by measuring the ability of cell extracts to end-join linearized plasmid monomers into multimers. mRNA and protein expression of components of NHEJ was determined using RT-qPCR and western blotting. Cytotoxicities of cisplatin and the Poly(ADP-ribose) polymerase-1 (PARP) inhibitor rucaparib were assessed using sulforhodamine B (SRB) assays. HR function was assessed using γH2AX/RAD51 foci assay.