SMAD2 and diabetic kidney disease: Studies have demonstrated that the potential therapeutic targets of the Sugar Kidney formula for treating renal fibrosis in diabetic nephropathy (DKD) include vascular endothelial growth factor (VEGFA), epidermal growth factor receptor (EGFR), fibronectin 1 (FN1), transforming growth factor beta 1 (TGFB1), signal transducer and activator of transcription 3 (SMAD3), signal transducer and activator of transcription 2 (SMAD2), and others.