EZH2 and neoplasm: Therefore, when cocultured with OT-I CD8+ T cells, expression of EZH2, but not its catalytically inactive mutants in Usp22-null tumor cells, totally diminished the increase in OT-I CD8+ T cell activation, including the production of granzyme B, IFN-γ, and TNF-α, cell surface expression of CD69, and OT-I mediated cytotoxicity (Figure 4, G and H, and Supplemental Figure 8, H and I).