KLRK1 and neoplasm: Furthermore, the transformation of normal cells into malignant cells or the epithelial mesenchymal transformation of tumor cells can lead to the absence of NK inhibitory signals on the cell surface as well as the upregulation of various ligands of NKG2D and cell adhesion molecule 1; this activates NK cell-mediated specific immune surveillance functions and can effectively inhibit tumor metastasis and malignant transformation of normal cells [287–289].