However, although the cytotoxicity of CIK cells were largely reduced by the blocking of NKG2D-ligands binding, it could not completely abrogate their lytic effects against tumor cells, suggesting the role of NKG2D interaction with its ligands was a main but non-exclusive mechanism mediating cytotoxic effects of CIK cells, and other molecules might be implicated. The gene discussed is KLRK1; the disease is neoplasm.