CXCR4 and glioma: Therefore, in expanding tumors characterized by a high presence of hypoxic regions, CXCR4 levels are significantly higher than in non-tumor cells, facilitating survival and escape from the primary tumor mass; indeed, in addition to facilitating distant metastasis, HIF-1 has been shown to induce CXCR4 in gliomas, leading to increased proliferation, resistance to apoptosis, and local invasion [30].