NK activating receptors recognize stress molecules (e.g., MIC-A/B and UL16-binding protein 1-4, ULBP1-4, recognized by NKG2D and CD112 and CD155 recognized by DNAM-1) upregulated on many tumor cells and trigger tumor targeting,50, 51, 52 while NK inhibitory receptors recognize matched “self” major histocompatibility complex (MHC) molecules and suppress tumor killing.53 The gene discussed is KLRK1; the disease is neoplasm.