Finally, by using the pCMVExt-Fc vector, we expressed two challenging proteins, the human ROR1-ED that is involved in cancer progression of a number of blood and solid malignancies (Hojjat-Farsangi et al., 2014) and the ligand for the NKG2D activating receptor on the surface of NK cells, ULBP2 (Sutherland et al., 2006). This evidence concerns the gene KLRK1 and cancer.