TGFB1 and idiopathic pulmonary fibrosis: Furthermore, an increased expression of principle pathways/components such as the TGFβ1/Smad pathway, platelet-derived growth factor (PDGF)/AKT pathway, galectin-3, transglutaminase-2, lysophosphatidic acid-1 (LPA-1), and lysyl oxidase-like- 2 (LOXL-2) have been reported in the bleomycin model and human IPF as critical contributors in driving fibrogenesis [8,15,16].