Additionally, rFGF4 treatment reduced renal fibrosis, as evidenced by decreased protein levels of the profibrotic markers type IV collagen (Col-IV) and transforming growth factor-β (TGF-β) (Supplementary Fig. 5c, d), as well as reduced mRNA levels of TGF-β, Col-IV, and α-SMA (Supplementary Fig. 5e). Here, TGFB1 is linked to renal fibrosis.