Fig. 1
From: TGF-β in pancreatic cancer initiation and progression: two sides of the same coin
Overview of the TGF-β signaling pathway. TGF-β signaling is transduced through two pathways of Smad (canonical) and non-Smad (non-canonical). In Smad pathway, cell surface complexes of TGFβRI and TGFβRII phosphorylate upon TGF-β ligand binding and activate Smad2 and Smad3. Smad4 and activated Smad2/Smad3 form a Smads complex, and then interacts with other transcription factors to regulate transcription of target genes. TGF-β signaling also activates non-Smad pathways, including PI3K-Akt, Ras-Erk, p38, JNK, and GTPases