Fig. 7
From: Fibrosis and bone marrow: understanding causation and pathobiology
The transforming growth factor-β (TGF-β) signaling pathway and its context-dependent regulation. (Left) A schematic diagram of TGF-β signaling. (Right) TGF-β signaling is regulated at several levels by context-dependent factors: (1) Different combinations of paired type I and type II receptors allow for diverse ligand binding as well as intracellular signaling. (2) Accessory proteins at the plasma membrane that regulate the binding efficiency and specificity of TGF-β to their receptors influence downstream responses. (3) Proteins that regulate the recruitment and access of R-Smads to TGF-β receptors. (4) Several proteins regulate TGF-β signaling by posttranslational modification of R-Smads or by preventing their association with TGF-β receptors. (5) A specific TGF-β response can be determined by the expression and activity of transcription cofactors