TGFB1 and idiopathic pulmonary fibrosis: TGF‐β1, a principle mediator in the pathogenesis of IPF and PH, is thought to contribute toward disease pathology, both directly through transcriptional activation of ECM components such as collagen, as well as indirectly through upregulation of the transcription factor HIF‐1α which is responsible for the activation of downstream profibrotic target genes, such as PAI‐1 in fibroblasts (Cutroneo et al. 2007; Liu et al. 2010).