CD8+ cytotoxic T cells had elevated expression of the cytotoxic markers PD-1, Gzmb, Gzmk, Prf1, Nkg7, Eomes, Irf8, Klrd1, Fyn, Nfatc1, Tnfrsf9, and Zap70, supporting their killing function against cancer cells [38,39,68,69,70,71,72,82]. This evidence concerns the gene PDCD1 and cancer.