TGFB1 and leiomyoma: Transforming growth factor beta (TGF-β) is produced in excess in the endometrium in women with fibroids and is associated with reduced levels of plasminogen activator inhibitor-1 (PAI-1), thrombomodulin and antithrombin III, both in vivo and in endometrial stromal cells treated in vitro with TGF-β [18].