DDX11 promotes homology-directed repair of DSBs and RAD51 foci formation nonredundantly with BRCA1 and BRCA2. (A) Quantification and representative micrographs of RAD51 focus formation in U2OS Ctrl and DDX11 KO recovering from 1 h treatment with cisplatin (2.5 μM). (Scale bar, 10 μΜ.) n = 2. Statistical analysis was performed using Student’s t test. Error bar shows average ± SD. (B) U2OS TRI DR-GFP cells were transfected with indicated siRNAs, and Sce-I was induced by adding doxycycline after 48 h of siRNA transfection. Fluorescence-activated cell sorting analysis was performed after 72 h of doxycycline induction (n = 3). Schematic representation of the assay is shown above. Error bars show average ± SEM. (C) Cell viability assay of HeLa Ctrl and DDX11 KO cells transfected with siCtrl, siBRCA1, and siBRCA2. Cells were treated with olaparib and Pyridostatin with the indicated drug concentrations for 72 h, and cell viability was measured using crystal violet staining (n = 3). (Bottom Left) Corresponding Western blot is shown. Statistical analysis was performed using Student’s t test. Error bars show average ± SEM.