KLRK1 and leukemia: Relevant receptors involved in anti-leukemia activity are NKp46, NKp30, and NKp44 (collectively called natural cytotoxicity receptors, NCR), whose surface-bound ligands are still not completely defined, NKG2D interacting with MICA/B and ULBPs, and DNAM-1 recognizing PVR (CD155) and Nectin-2 (CD112) [21,22,23,24].