Moreover, variation in the expression of NKG2D ligands (NKG2D-L; e.g., MICA/B, ULBP1-3) might be due to the upregulation of matrix-bound metalloproteinases (MMPs) by cancer cells, which can shed NKG2D-L from the tumor cell surface leading to decreased membrane expression, consequently reducing NK cell recognition and activation [31]. Here, KLRK1 is linked to neoplasm.