TGFB1 and pulmonary fibrosis: Furthermore, activation of different types of integrin by collagen triggers significant signaling pathways: a3b1 integrin signals trigger phosphorylation of β-catenin and SMAD2 to promote EMT in a model of lung fibrosis, a5b3 integrins induce EMT by facilitating Src-mediated phosphorylation of TGF-βRII, creating a docking site for ShcA and GRB2 and p38 MAPK pathway, and integrins a5b6 and a5b8 induce the proteolytic release of the latency-associated peptide (LAP), and activate TGF-β at the cell membrane through the protease activity of MMP-14 [131].