KLRK1 and neoplasm: Next to CD16 (FcγRIIIA), which interacts with Fc fragments of several IgG subclasses, triggering the ADCC (24), the natural cytotoxicity receptors (NCR) NKp30 (CD337), NKp44 (CD336), NKp46 (CD335), NKp80, DNAM-1 (CD226) and NKG2D (CD314) are the major activating receptors and are able to recognize induced self-ligands that are downregulated on healthy cells and highly expressed on tumor cells (25).