CHEK1 and familial pancreatic carcinoma: To exclude the possible cell-specific role of APE2 in the ATR DDR pathway, we performed similar experiments in another human pancreatic cancer MiaPaCa2 cells and found that APE2 was also important for the H2O2-induced ATR-Chk1 DDR pathway in MiaPaCa2 cells (Supplementary Figures 1A,B).