PARP1 and breast cancer: We predicted that there would be synergistic activation of apoptosis of the breast cancer cell lines with mtp53 in the presence of talazoparib plus temozolomide because this alkylating agent has been shown to provoke PARP trapping.27 We found that combination treatment with talazoparib plus temozolomide induced synergistic activation of apoptosis only in the presence of mtp53 and only when MCM2–7 processivity was not inhibited by ciprofloxacin (Fig. 6a–c).