NCR2 and neoplasm: NK cell activation also results from the engagement of activating receptors, such as the activating isoforms of KIRs, the signaling lymphocyte-activating molecule-related receptors NKG2D, DNAX accessory molecule-1 (DNAM-1), and the natural cytotoxicity receptors NKp30, NKp44, and NKp46, which recognize stress-inducible ligands on tumor cells that are scarcely expressed in healthy cells.