Fig. 2

MRE11A deficiency increases DNA damage signals 12 h after MNNG treatment. A Representative western blotting pictures of chromatin binding and whole-cell MSH2, MLH1, and MRE11 proteins 12 h after DMSO or 200 nM MNNG treatment of HeLa cells. The level of histone H3 was set as an internal control. The right graph shows the quantification of the fold change in the ratio of chromatin binding to the whole-cell proteins MSH2, MLH1, and MRE11A after exposure to 200 nM MNNG. B Representative western blotting of the phosphorylation levels of CHK1 12 h after DMSO or 200 nM MNNG treatment. The alteration of phosphorylation level was calculated as p-CHK1 level normalized by total CHK1 protein after 200 nM MNNG treatment minus that with only DMSO treatment. The right graph shows the quantification of protein level changes relative to siNC. C Representative immunofluorescence images of 53BP1 foci in G1 phase 12 h after DMSO or 200 nM MNNG treatment. The right graph shows the quantification of the number of 53BP1 foci per cell in G1 phase (CYCLINA-). At least 250 cells were counted for each group. Data are shown as mean ± SD, *P < 0.05, **P < 0.01, ***P < 0.001, using unpaired two-tailed Student’s t test