SMAD3 and myocardial infarction: In another similar study, a closed-chest model of reperfused myocardial infarction in SMAD3 null mice demonstrated that TGF-β1 stimulation was associated with upregulation of procollagen III but not in Smad3 null mice, which indicates that TGF-β-mediated SMAD3 signaling plays an important role in extracellular matrix protein synthesis [79].