CXCL8 and neoplasm: Hypoxia leads to the secretion of many growth factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), cytokines, such as interleukin 8 (IL-8), and other pro-angiogenic mediators, such as sphingosine-1 phosphate (S1P), leading to the proliferation, migration and tumor-like formation of the nearby endothelial cells (5–8).