Natural killer group 2D (NKG2D) is a principal activating receptor broadly expressed on NK cells and cytotoxic lymphocytes (for example, CD8+ T cells); it recognizes stress-inducible ligands on tumor cells (e.g., MICA/B and ULBP1-6) and triggers potent cytotoxicity 77. The gene discussed is KLRK1; the disease is neoplasm.