The ligands for NKG2D in mice, including retinoic acid early inducible-1 (RAE-1) proteins (RAE-1α, β, γ, δ, and ε), minor histocompatibility antigen (Ag) H60 and murine UL16-binding protein-like transcript-1 (MULT-1) glycoprotein, are expressed poorly by most normal cells but up-regulated in tumor cells, infected cells or by cells under stress [7], [8], [9]. Here, KLRK1 is linked to neoplasm.