In this study, we established a rat model of diabetic nephropathy by using STZ and selected MG132 as the specific ubiquitin proteasome inhibitor for blocking the TGF-β/SMAD signaling pathway, in order to explore the relationship between the UPP and the TGF-β/SMAD signaling pathway in diabetic nephropathy. This evidence concerns the gene TGFB1 and diabetic kidney disease.