Western blot results indicate that the level of TGF-β1, phosphor-Smad2, and Smad4 in diabetic nephropathy group were significantly elevated compared to normal control group, while the level of Smad7 was significantly decreased, suggesting that the TGF-β1/Smad2 signaling pathway was activated in the diabetic nephropathy group (Figure 6). This evidence concerns the gene SMAD4 and diabetic kidney disease.