NCR2 and neoplasm: The activating receptors, notably the natural cytotoxicity receptors (NCRs), including NKp46 (6), NKp30 (7), NKp44 (8), natural killer group 2 member D (NKG2D) (9), DNAX accessory molecule-1 (DNAM-1), and CD244, recognize ligands expressed on tumor cells.