Activating signals are generated through NK group 2 member (NKG2D), which recognize the stress-inducible molecules MHC class I chain-related proteins (MICA and MICB) and the UL-16-binding proteins 1-4 (ULBP1-4), also known as RAET proteins, or through natural cytotoxicity receptors (NCRs) that recognize viral hemagglutinin and as yet undefined tumor-associated ligand. This evidence concerns the gene KLRK1 and neoplasm.