SMAD3 and endometriosis: Importantly, the consequent extravasation and aggregation of platelets can finally induce fibrosis in endometriosis lesions through TGF-β1 release and induction of the TGF-β1/Smad3 signaling pathway, which is a potent inducer of epithelial–mesenchymal transition and fibroblast-to-myofibroblast transition in endometriotic cells [40,43,44].