KLRK1 and neoplasm: Because we were able to document cytotoxicity of the sIL15_TRACK NK cells within 24 hours after the infusion, and document the presence of sIL15_TRACK NK cells at the tumor site 7 days after the final infusion, we assessed the sIL15_TRACK NK cells for the expression of 3 activating receptors, namely NKG2D, DNAM-1, and NKp30, among other antigens and the NSCLC tumor biopsy for its expression of the cognate ligands to those 3 receptors.