(Top) The DR-GFP reporter assay. SceGFP is a modified version of the GFP gene, which contains an I-Sce site and an in-frame premature stop codon that can be removed by HR-mediated repair of the I-SceI–induced DSB using the internal GFP fragment (iGFP) placed downstream from the SceGFP cassette. (Middle) The experimental setup used to monitor HRR in the HeLa DR-GFP cell line. (Bottom) The percentage of GFP+ cells for each experimental condition (siRNA +/− I-SceI) was measured by flow cytometry (FACS) following the experimental procedure detailed in the top right panel and normalized to the siCtrl + I-SceI conditions, in two human cell lines: HeLa and U2OS. (***) P < 0.0001, (**) P < 0.001, (*) P < 0.01, (ns) nonsignificant.
