Fig. 1

TGF-β signaling in fibroblasts. Latent TGF-β binds to its type I and II receptors, and activates the canonical Smad3/4 pathway and the noncanonical TGF-β–activated kinase-1 (TAK1)/p38/c-Jun N-terminal kinase (JNK) and NADPH oxidase 4 (NOX4)/reactive oxygen species (ROS) pathway resulting in induction of fibrogenic genes, such as α-smooth muscle actin (α-SMA) and collagen. (Reprinted from Leask A. [10])