EGFR and idiopathic pulmonary fibrosis: Stimulation of normal lung fibroblasts with conditioned medium obtained from NU-ABC or IPF-ABC harvested at day 14 induced fibronectin (Fig. 2m, n) and collagen (Fig. 2m, o) expression in lung fibroblasts as well as induced EGFR phosphorylation (Fig. 2p and Supplementary Fig. 5), a finding consistent with significantly increased secretion of amphiregulin by IPF-ABC bronchospheres (Fig. 2f).