VEGFA and endometriosis: They produce numerous cytokines and growth factors in the peritoneal microenvironment, such as interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-12 (IL-12), tumour necrosis factor-alpha (TNF-α), vascular epithelial growth factor (VEGF) and transforming growth factor-beta 1 (TGF-β1) to induce endometriosis lesion implantation, growth and angiogenesis (2, 17, 30).