They can contribute to anti-tumour activity in a direct way (by granule proteins, granzyme A, involved in strong cytotoxic activity) [182] as reported in human colon carcinoma cells [154,155] (Table 1) or in an indirect way with CCL5, CXCL9 and CXCL10 expression that contribute to the recruitment of tumour-reactive CD8+ T cells, as reported in mouse models of melanoma [177]. This evidence concerns the gene CD8A and neoplasm.