For example, tumor cell surface expression of NKG2D ligands, either in human or in mice, could be therapeutically upregulated to enhance NK cell activation, by treating tumor cells with alkylating agent (102), proteasome inhibitors (103), hyperploidy-inducing agents (104), histone deacetylation inhibitors (105), or inhibitors for glycogen synthase kinase-3 (106). The gene discussed is KLRK1; the disease is neoplasm.