Moreover, according to genotypic and phenotypic evidence of a more close reproduction in vitro of the in vivo tumor characteristics of cultures enriched in CSCs, as compared with established cell lines (Lee et al., 2006), recent studies addressed the role of CXCL12 and its receptors in this GBM cell subpopulation (Figure 2). This evidence concerns the gene CXCL12 and neoplasm.