(B) The effect of H2AX E141 ADP-ribosylation on γH2AX following oxidative stress. γH2AX or H2AX was detected using Western blotting and immunostaining assays. The intensity of γH2AX levels were examined by Western blotting normalized by β-actin and averaged. Values are mean ± SD of three assays. P-values were calculated using Student's t-test. **P < 0.01 (left panel). The number of γH2AX foci examined in immunostaining assay was counted by Image J software and graphed by GraphPad Prism 8. 