SMAD3 and polyostotic fibrous dysplasia: In addition, PFD and/or AGP inhibited the activation of HSCs by blocking the TGF-<i>β</i>/Smad signaling pathway, and the combined treatment of PFD and AGP synergistically inhibited the phosphorylation of Smad2 and Smad3.<h4>Conclusion</h4>The combined application of PFD and AGP exerted superior inhibitive effects on HSC activation and liver fibrosis by mediating the TGF-<i>β</i>/Smad signaling pathway as compared to monotherapy.