TGFB1 and renal fibrosis: The TGF-β1 signaling pathway is the core molecule of renal fibrosis in DKD and can regulate fibrosis by promoting the overexpression of the extracellular matrix, which enhances the dedifferentiation of tubular epithelial cells and glomerular endothelial cells, and promotes cross-linking between collagen and elastin fibers [4,62].