KLRK1 and neoplasm: The natural killer group 2, member D (NKG2D) system consists of the NKG2D receptor expressed on natural killer (NK) cells, cluster of differentiation 8+ (CD8+) thymus (T)-cells and natural killer thymus (NKT) cells and NKG2D ligands (NKG2D-Ls), frequently upregulated in stressed cells such as viral or bacterial infected cells and tumor cells [1].