CXCL12 and neoplasm: The above studies suggest that the cells which are at the center of tumor mass require blood supply for transport of O2, nutrients, and growth factors; therefore, HIF-1α activates angiogenic factors such as VEGF, ANGPT-2, SDF-1α, SCF, and PDGF-β to facilitate neoangiogenesis, endothelial cell proliferation, and endothelial cell migration.