With respect to the determinants against infiltration of NK cells into tumors, C-X-C motif chemokine ligand 9 (CXCL9), CXCL10, or CXCL11 (which are all ligands to the C-X-C motif chemokine receptor 3 (CXCR3), a receptor that plays a crucial part in the recruitment of NK cells in solid tumors) have shown substantial secretion in an experimental model of lymphoma, lung adenocarcinomas, and melanomas tissues (27–29). This evidence concerns the gene CXCL9 and melanoma.