CLEC2D and neoplasm: Some of the NK cell receptors are already found to be valuable for leukemia treatment and tumor surveillance, which were PD-1, 2B4 (CD244), CS1(CD319), LLT1 (CLEC2D) that regulate NK cell cytotoxicity, and NKp44, NKp30, and NKp46 known as natural cytotoxicity receptors (NCRs).