While CXCR4 and CXCR7 receptors are moderately expressed on normal endothelial cells, CXCR7 expression on these cells inside of the TME is significantly increased, and it has recently been proposed as a biomarker of tumor vasculature in cancers, like renal carcinoma and gliomas [212]. Here, CXCR4 is linked to central nervous system cancer.