TGFB1 and endometriosis: Hyperactive TGF-β signaling induces fibrogenesis by stimulating stromal fibroblasts to produce collagen [22], which is a vital component of the extracellular matrix [23].It has been widely believed that the local immunological milieu is type 2 T helper (Th2)-cell-skewed, and Th2 lymphocytes are reported to be involved in endometriosis [14,16,17,18,24,25,26].