CHEK1 and cancer: Previous studies show that ATR inhibitor VE-822 sensitizes cancer cells to radiation or chemotherapy drugs such as CPT (Fokas et al., 2012; Josse et al., 2014), and that Chk1-KD by siRNA or Chk1 inhibition by small molecule inhibitor AZD7762 has been shown to function in a synthetically lethal manner with GEM in pancreatic cancers (Venkatesha et al., 2012).