KLRK1 and neoplasm: To determine if the purified NKG2D-Fc-RO protein could bind to murine NKG2D ligand-expressing tumor cells, we selected a Rae-1 (a murine NKG2D ligand)-expressing ovarian tumor cell line (MOVCAR) and one Rae-1-negative tumor cell line (B16F10) for our studies (Figure 2A).