When tumor-special CD8+ T cells, isolated from TNFR2−/− mice, TNFR1−/−, or wild-type mice, were cultured with specific antigens in vitro, IFN-γ levels produced by TNFR2−/−CD8+ T cells was less than TNFR1−/− or wild-type CD8+ T cells (54), indicating that TNFR2 was also necessary for the optimal production of IFN-γ to clear tumor antigens during the T cell activation phase. This evidence concerns the gene IFNG and neoplasm.