NKG2A is an intracytoplasmic tyrosine-based inhibitor motif, expressed in NK cells and selectively in CD8+ CTLs in tumor microenvironment, which can block the immune ability of NK cell and CD8+ T cell if it binds its ligand (HLA-E) overexpressed in carcinoma of lung, cervix and head/neck [69]. This evidence concerns the gene KLRC1 and neoplasm.