Effects of exogenously expressed SLFN11 in FANCD2^−/− hTERT RPE-1 cells. (A) DOX-induced expression of wild-type SLFN11 in lentivirally transduced FANCD2^−/− hTERT RPE-1 cells (clone #2B7). Cells were stimulated or not with doxycycline (2 μg/mL) for 48 hours. WT, wild-type hTERT RPE-1 cells. (B) Growth curve of FANCD2^−/− hTERT RPE-1 cells transduced with wild-type SLFN11. Means ± standard error of the mean (SEM) of triplicate cultures with or without DOX are shown. (C) DNA fiber analysis to quantify fork degradation/protection. The CldU tract length was measured in FANCD2^−/− RPE1 cells with or without expression of wild-type SLFN11. Cells were stimulated or not by HU treatment. Means ± SEM of more than 450 fibers were quantified from 3 independent experiments. P values were calculated by unpaired, 2-tailed Student t tests.