BAP1 and cancer: Notably, BAP1-ablated DT40 cells were highly sensitive to the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib, further corroborating the HR activity of BAP1, as cancer cells with inactivating mutations in BRCA1 or BRCA2, which are thus deficient in HR, were found to be hypersensitive to PARP inhibition73–75.