SMAD2 and Myocardial fibrosis: The expression of TGF-β1 (p < 0.05, p < 0.01) and P-Smad2/3 (p < 0.01) proteins was significantly lower in the VDDE group and CONS group than in the VDDS group (Figure 7D–G), suggesting that aerobic exercise training may ameliorate myocardial fibrosis in vitamin D-deficient mice by inhibiting the TGF-β1-Smad2/3 signaling pathway.