CXCR4 and neoplasm: More than one hundred kinds of target genes associated with tumor growth and metastasis can be regulated and activated by HIF-1α, most of them were related to tumor progression and metastasis, such as gene involved in angiogenesis (VEGF, PDGF, PIGF), extracellular matrix degradation gene (MMPs), metastatic gene(SDF1, CXCR4, LOX), epithelial-mesenchymal transition gene (SNAIL, SIP) and so on12.