These results confirm that the recurrence of glioblastoma is associated with a specific switch of the pattern of angiogenic factors expression, from VEGFR2-HIF1α to CXCL12-CXCR4 pathway, i.e., angiogenic switch to proangiogenic and protumoral CXCL12-CXCR4 signaling [225]. The gene discussed is CXCL12; the disease is glioblastoma.