SMAD7 and diabetic kidney disease: TFPI2 enhances TGF-β/Smad signaling by preventing SMURF2 (SMAD-specific E3 ubiquitin protein ligase 2)-SMAD7 (SMAD family member 7) interactions, facilitating TGF-β pathway activation, and promoting endothelial-to-mesenchymal transition and fibrosis, particularly in diabetic nephropathy (Figure 2(6)) [10].