CXCR4 and central nervous system cancer: As before we confirmed that mNS GSC have a higher expression level of the stem cell markers CXCR4, MELK, PTCH, CD44, CD133, MSl1 and CD90 [19, 29–32], while GL261 GDC expressed higher level of the differentiated glioma marker glial fibrillary acidic protein (GFAP) (Fig 2A).