KLRD1 and neoplasm: This ligand, aberrantly overexpressed by tumor cells in several solid tumors, interacts either with the inhibitory CD94/NKG2A receptor, or the activating CD94/NKG2C (NK group 2 member C) receptor selectively expressed by immune cells with cytolytic functions such as NK cells, NKT (natural killer T) cells and a subset of T cells (9).