SMAD3 and idiopathic pulmonary fibrosis: In contrast, work by Reka and colleagues [19] suggested that troglitazone and rosiglitazone antagonize Smad3 signaling during TGF-β1-induced EMT in A549 cells in a PPARγ-dependent fashion, leaving the precise mechanism(s) unresolved, although mechanistic observations derived from cell lines of cancerous origin may not be effectively translated to the in vivo setting in the context of IPF.