SMAD2 and pulmonary fibrosis: Although ART has been proved to interrupt TGF-β signaling in pulmonary fibrosis models (Li et al., 2014; Wang et al., 2015), the mechanism of whether the ART directly inhibit phosphorylation of Smad2/3 (pSmad2/3) in MSCs in ACLT mice needs be further elucidated in the following study.