TGFB1 and lupus nephritis: Increased IL-6, α-smooth muscle actin, fibronectin, and collagen I and III expression in the kidney was detected before TGF-β1 expression, suggesting that TGF-β1 may amplify fibrotic processes once fibrosis is established, but it does not appear to play a role in the initiation of kidney fibrosis in lupus nephritis.