Indeed, the ATR inhibitors NU6027 and VE-821 have been shown to increase the cytotoxic effects of the PARP inhibitors rucaparib and veliparib in various cancer cell lines,62–64 and resistance of Schlafen 11-deficient cells to PARP inhibitors is overcome by inhibition of ATR65 but, to our knowledge, the effects of ATR inhibition on olaparib-treated ATM-deficient cells has not been determined. Here, ATR is linked to cancer.