The results showed that compared with non-radiation, more γ-H2AX foci were observed in PCI-34051 and radiation treated A549 cancer cells (Supplementary Fig. 9), HepG2 cancer cells (Supplementary Fig. 10), U87 cells (Supplementary Fig. 11), and HeLa cells (Supplementary Fig. 12) and MCF-7 cells (Supplementary Fig. 13), indicating that decrotonylation of Ku80 K568cr is required for activation of DNA DSB repair. This evidence concerns the gene XRCC5 and cancer.