PARP1 and breast cancer: The poly(ADP-ribose) polymerase (PARP) plays an important role in many cancer types, including ovarian cancer, breast cancer, pancreatic cancer, and prostate cancer.733 Furthermore, PAR chains are rapidly degraded by PAR glycohydrolase which restores PARP and PARylated proteins to a de-(ADP-ribosylated) state to promote SSB repair.