Moreover, by Western blot, we also tracked the dynamics of γ-H2AX, a marker for DNA damage, to measure the extent of DNA damage and the speed of damage repair; and found that irradiation elevated γ-H2AX and H2Bub1 proteins in both the parent and USP22−/− cancer cells, while more γ-H2AX and H2Bub1 were induced in USP22−/− A549 cells (Fig. 6c, left panel) and USP22−/− H1299 cells (Fig. 6d, left panel) than their parent cells at 2 h post-irradition. This evidence concerns the gene USP22 and cancer.