In addition, colorectal carcinoma-derived cancer-initiating cells (CICs) were more susceptible to freshly purified allogeneic NK cells than the non-CIC counterpart of the tumors, due to the higher expression of ligands for NKp30 and NKp44 in the natural cytotoxicity receptor group of activating NK receptors in CICs (40). This evidence concerns the gene NCR2 and cancer.