CXCL12 and neoplasm: Many cellular factors and molecular events drive tumor stem-like cells to express endothelial phenotypes; these factor and events include vascular endothelial (VE)-cadherin, stromal cell-derived factor 1 (SDF-1), and Twist1-Bmi1 and epithelial-mesenchymal transition (EMT), hypoxia, or oxygen-glucose deprivation [16–21].