CD133 (prominin 1) is a membrane glycoprotein involved in retinal development, whose overexpression is related to aggressiveness of ovarian, colorectal, prostate, and lung cancer, and glioblastoma, representing a signature for putative CSCs in these neoplasms (89); the chemokine CXCL12 and its receptors CXCR4/CXCR7 are involved in self-renewal and migratory behavior of normal stem cells and CSCs (90, 91) acting via autocrine/paracrine mechanisms (52, 55). This evidence concerns the gene PROM1 and glioblastoma.