SMAD2 and idiopathic pulmonary fibrosis: PD-L1 levels were higher in IPF fibroblasts than in healthy controls. TGFβ induces the expression of PD-L1 in human and murine fibroblasts in a Smad2/3- and YAP/TAZ dependent manner. TGFβ induced fibroblast extracellular vesicles contain PD-L1 which can inhibit T cell proliferation and activated fibroblast migration.