CXCL12 and melanoma: For instance, in vitro experiments have shown that bone-derived soluble factors not only elicited the chemotactic response of osteotropic melanoma cells, but promoted their ability to reprogram non-osteotropic melanoma cells to express CXCR7 and, consequently, acquire bone osteotropism mediated by the CXCL-12 chemotactic gradient (43).