CXCR4 and neoplasm: These soluble factors are involved in paracrine signaling or in autocrine loops to contribute to tumor progression [13], stromal cell-derived factor-1alpha (SDF-1α) (CXCL12) is a member of the CXC chemokine family, the chemotactic effects of which are mediated by interaction with chemokine receptor 4 (CXCR4).