FAN1 deficiency augments the resistance of EXO1-deficient TK6 and HAP1 cells to MNU and TG. (A) Clonogenic assay showing the response of WT, FAN1−/−, EXO1−/−, and FAN1−/− EXO1−/− TK6 cells to MNU. (B and C) MTT assays showing the response of WT, FAN1−, EXO1−, EXO1− FAN1− and MSH6− HAP1 cells to MNU (B) and TG (C). The results of three independent experiments each carried out in triplicate are shown. Error bars represent the standard error of the mean.