A, Survival of PDAC cell lines treated with the indicated doses of gemcitabine (GEM). IC50 values are provided. Cell survival was calculated by measurement of dsDNA content using PicoGreen. B, γ-H2AX foci. MiaPaCa2 cells cultured for 48 hours and treated with gemcitabine for the final 18 hours. C, ROS levels in MiaPaCa2 cells by DCF fluorescence and under the indicated conditions for 48 hours. Cells were treated with gemcitabine (1 µmol/L) for the final 18 hours. Error bars represent ± SEM of triplicate wells from a representative experiment. (N.S., nonsignificant; *, P < 0.05; **, P < 0.01; ***, P < 0.001). See also Supplementary Fig. S1.