PARP1 inhibitors attenuate AKT phosphorylation via the upregulation of PHLPP1

► PARP1 inhibitors cause a cytotoxic effect independent of DNA repair impairment. ► PARP1 inhibitors attenuated AKT-FOXO3A signaling by activating PHLPP1. ► PHLPP1 regulates the sensitivity of cancer cells to PARP1 inhibitors.