CD8A and melanoma: Furthermore, gene enrichment related to effector function and immunological synapse formation was found in CD226hiCD8+TILs from HCmel12hgp100 melanoma-bearing mice; however, unlike the previous studies on the inverse correlation between CD226 and co-inhibitory receptor expression on the surface of CD8+TILs, the expression of co-inhibitory receptor genes was unaltered in CD8+TILs regardless of CD226 expression.