Moreover, TGF-β1 is overexpressed in the heart in a high-cholesterol-fed porcine model of myocardial infarction, and its downstream Smad2 and Smad3 are activated, thereby increasing collagen synthesis and the levels of Col1a1, Col3a1, and α-SMA (37). Here, SMAD3 is linked to myocardial infarction.