Fig. 8

Efficiency of DSB repair in ID3-depleted cells. a A diagram of the fluorescence-based assay for measuring levels of DSB repair via homologous recombination (HR) is shown. b The efficiency of HR repair was measured by FACS analysis in DR-GFP-U2OS cells transfected with either control or ID3 siRNA (lower panel) (n = 3). The levels of endogenous MDC1 and ID3 were analyzed by western blotting (upper panel). c A diagram of the assay for measuring non-homologous end joining (NHEJ) repair using an EJ5-GFP reporter is shown. d The efficiency of NHEJ repair was measured by FACS analysis in HeLa cells that contained EJ5-GFP and had been transfected with either control or ID3 siRNA (lower panel) (n = 3). The levels of endogenous MDC1 and ID3 were analyzed by western blotting (upper panel). e Chromosome spreads from control or ID3-depleted HeLa cells exposed to IR are shown. Images (left panel) and a plot (right panel) of the average frequencies of chromosomal breaks (n = 50). Scale bars: 10 μm. f Array CGH profiles of clones derived from control or ID3-depleted GM00637 cells are shown. g A schematic representation of the role of ID3 in regulating the DDR functions of MDC1 is shown. The presence (left pathway) and absence (right pathway) of ID3 are compared. Uncropped blots of this Figure accompanied by the location of molecular weight markers are shown in Supplementary Fig. 14. Data are presented as means ± s.d. P values are based on Student’s two-tailed t-test: **P < 0.01, ***P < 0.001