CXCR4 and neoplasm: SDF-1 promotes vascular morphogenesis and sprouting of endothelial cells[66], [70], [71], [72] as well as vascular sprouting from embryoid bodies and aortic rings [73], [74]; SDF-1-CXCR4 signalling plays a critical role in tumor angiogenesis in vivo[75], [76].