SMAD3 and diabetic kidney disease: Correlation analysis showed that GXP4 expression inversely correlated with activation of Smad3 signaling (p-Smad3) and the fibrosis marker Col-1 (Figure 1E). Electron microscopy (EM) found morphological alterations associated with ferroptosis, such as a reduction in mitochondria quantity, an increase in bilayer density, and decrease in mitochondrial cristae in the kidney tissues of patients with DKD and IgAN but not in patients with MCD (Figure 1D).