CXCL9 and melanoma: Other studies investigated the expression of orphan receptors as well as known chemokine receptors and chemokine ligands in melanoma metastases, leading to the identification of several molecules differentially expressed in metastatic melanoma, such as GPR18, GPR34, GPR119, GPR160, GPR183, P2RY10, CCR5, CXCR4, CXCR6, CCL4, CCL5, CCL14/15, CXCL8, CXCL9, CXCL14, and XCL1/2 [5].