CXCR4 and central nervous system cancer: In the context of glioma, CXCL12/CXCL12-receptor (CXCR4/CXCR7) autoregulatory signaling has been demonstrated to be important for glioblastoma survival [8, 29, 30] and angiogenesis [31], while CX3CL1/CX3CR1 axis signaling in glioma cells controls glioma cell invasion [32].