HR and NHEJ DNA repair assay

HR and NHEJ assays were used to determine the HR and NHEJ repair efficiency. The DNA repair assays were performed as previously described. Briefly, U2OS cells integrated with direct repeat GFP (DR-GFP) or EJ5-GFP reporters were infected with the indicated plasmid or siRNA. Then, cells were transfected with I-Scel and p-cherry expression vector. Doxycycline (DOX) was added to induce I-SecI expression. Forty-eight hours after DOX was added, the percentage of GFP- or RFP-positive cells was analyzed by FACS. HR and NHEJ efficiency were presented as the percentage of GFP- and RFP-positive cells. Repair frequencies presented are means ± SD of at least three independent experiments.