TGFB1 and myocardial infarction: Western blot analysis showed that myocardial expression of TGF-β1 and phosphorylated Akt was significantly upregulated in the Ad-Null mice 4 wk post-MI, however, Ad-shPDE5a treatment completely reversed the TGF-β1 upregulation while further increased the expression of phosphorylated Akt (Fig 5A and 5B).