SMAD3 and myocardial infarction: Up-regulation of phosphorylation of Smad2 and Smad3 were observed in ACFs treated with TGF-β1 as well as in infarcted cardiac tissues of WT mice 7d after MI, and CAR3 knockout strikingly inhibited the activation signal of Smad2 and Smad3 (Figure 6A, B).