CXCL8 and endometriosis: Many pro-angiogenic factors, including fibroblast growth factors (FGF), platelet-derived endothelial cell growth factor (PDGF), transforming growth factor alpha and beta (TGF-α and TGF-β), hepatocyte growth factor (HGF), erythropoietin, angiogenin, tumor necrosis factor alpha (TNF-α), and IL-8 have been detected at increased concentrations in peritoneal fluid of women with endometriosis [54].