CXCL12 and central nervous system cancer: During the glioma early-growth phase, activated tumor cells are believed to first organize into cuffs around normal blood vessels to obtain nutrients (5) and generate massive tumor blood vessels by promoting endothelial cell proliferation by secreting vascular endothelial growth factor (VEGF), angiopoietin-2 (ANG-2), and stromal cell-derived factor 1 (SDF-1α) (6) and recruiting circulating endothelial progenitors (7) to provide essential nutrients for tumor growth and progression.