KLRK1 and neoplasm: We observed that tumor target cell lines that express the ligands for NKG2D and NKp30 such as FO-1 and RAJI, were more susceptible to HPS2 NK cells than other tumor cell lines mainly expressing the ligands for NKp46 (M14, P815, B-EBV lymphoblastoid cell lines) that were not killed by patients' NK cells.