TGFB1 and renal fibrosis: Additionally, another animal study indicated that cadmium chloride exposure triggers renal fibrosis by activating the TGF-β1/mothers against decapentaplegic homolog (Smad)/collagen IV signaling pathway, stimulating proinflammatory mediators, inhibiting the activation of nuclear factor erythroid 2-related factor 2, and enhancing apoptotic signaling (108).