We also found that IPF-derived HLMFs, without TGFβ1 stimulation, have significantly higher constitutive total Smad2/3 protein expression, greater Smad2/3 expression within the nucleus and higher Smad2 and Smad3 mRNA expression when compared to NFC control cells. Here, TGFB1 is linked to idiopathic pulmonary fibrosis.