In GBM cell lines, CXCR7 controls proliferation through a functional cross-talk with CXCR4 [23], and in the developing rat brain, a cross-talk between CXCR4 and CXCR7 might account for the regulation of SDF-1α-dependent neuronal development [24]. This evidence concerns the gene CXCR4 and glioblastoma.