(R) HR analysis. U2OS-DR-GFP cells were transfected with I-SceI, BRCA1 and siBRCA1 in KLF4-wild-type and depletion condition, respectively. GFP positive cells representing HR repair rate were measured by flow cytometry 48-72 hour after then. Overexpression of BRCA1 restores the HR efficiency in KLF4 knockdown cells. Data are mean ± SEM; n=3, p values were labeled in figure, one-way ANOVA assay. 