Skip to main content
. 2015 May 20;2015:654594. doi: 10.1155/2015/654594

Figure 1.

Figure 1

TGF-β signaling. Active TGF-β1 binds to its cell surface type II receptor (TβRII) inducing the activation of TGF-β type I receptor (ALK5/TβRI) forming a heterotetrameric complex. Active TβRI from the complex then triggers the activation of the Smad pathway: TβRI phosphorylates the receptor associated-Smads (R-Smads) Smad2,3 which in turn promotes their release from the complex with SARA from the inner face of plasma membrane. Phosphorylated Smads interact with co-Smad4 forming a heteromeric complex to be translocated into the cell nucleus, where, through the interaction with other transcription factors and corepressors or coactivators, it modulates gene expression. Active TGF-β-receptors can also activate the non-Smad signaling pathways, such as ERK1,2, p38, JNK, and NF-κB. Furthermore, the active receptor complex can activate PI3K provoking the activation of AKT and the small Rho GTPases. The activation of non-Smad signaling pathways can, in turn, initiate transcriptional or nontranscriptional activity to regulate gene and cellular responses.