The mortality of BNL hepatoma cells was decreased significantly after the application of anti-NKG2D monoclonal antibody, which suggested that the expression of NKG2D receptors on NK cells blocked by a monoclonal antibody might inhibit the secretion of IFN-γ and decrease the cytotoxicity effect on BNL hepatoma cells. The gene discussed is KLRK1; the disease is hepatocellular carcinoma.