Fig. 6.

Pre-pro transforming growth factor-beta (TGF-β) loses its pre-region and gets converted to pro-TGF-β. Pro TGF-β, under glycosylation, gets converted to low glycosylated pro-TGF-β. The low glycosylated pro-TGF-β again undergoes glycosylation and is converted to high glycosylated pro-TGF-β. Furin cleaves the active region of TGF-β from the pro-region and forms latent TGF-β [106–109]. Pirfenidone at this stage stops the maturation of TGF-β by inhibition of furins [103–105]. After the formation of latent TGF-β, it is secreted outside the cells and the active form of TGF-β is released as shown in Fig. 1