TGFB1 and endometriosis: HPMC and MeT-5A cells exposed to physiological concentrations of TGF-β1 expressed significantly higher levels of VEGFA mRNA transcripts and secreted significantly higher levels of VEGF-A protein, confirming that that peritoneal mesothelium may be a potential a source of increased VEGF-A levels in the peritoneal fluid of women with endometriosis.