CXCR4 and neoplasm: • Increases tumor cell proliferation, and reduces trail-mediated apoptosis • Induces EGFR activation • Enriches the CSC sub-population • Increases ERα stability and confers insensitivity to endocrine therapy • Leads to increased endothelial cell migration (angiogenesis)------------------------------------------------------------------- • Inhibits cell proliferation, possibly through CXCL12 sequestration • Antagonizes the ability of CXCR4-expressing tumor cells to degrade matrix