Within human glioblastoma tissues, an increased expression of CXCL12 and CXCR4 was localized not only in the regions of tumor necrosis and apoptosis, but also in the areas characterized with high microvessel density, what indicates the importance of this chemokine in the development of these tumors [201,202]. The gene discussed is CXCL12; the disease is glioblastoma.