KLRK1 and neoplasm: Importantly, tumors including GBM (Chitadze et al., 2015) often secrete NKG2D ligands, for example, through cleavage by ADAM10 and ADAM17 molecules, which often results in decreased surface expression of NKG2D on NK cells and reduced NKG2D-mediated anti-tumor response (Waldhauer and Steinle, 2006; Waldhauer et al., 2008; Liu et al., 2010).