We treated HLFs with IPF conditioned distal epithelial media supplemented with TGFBRI inhibitor (SB431542), AREG neutralizing antibody (iAREG), or SB431542 + iAREG (Fig. 4f) and found that treatment reduced fibroblast activation (Fig. 4g–j). The gene discussed is AREG; the disease is idiopathic pulmonary fibrosis.