CXCR4 and neoplasm: Following the binding of CXCL12 to CXCR4 on the tumor cell surface, the resultant CXCR4-CXCL12 complex activates various intracellular signaling cascades, which in turn enhance the proliferation, migration, and invasion of tumor cells, along with promoting tumor angiogenesis and metastatic spread to distant sites (92, 93).