ZEB1 and idiopathic pulmonary fibrosis: In IPF tissue, we detected strong nuclear expression of ZEB1 not only in fibroblastic foci (Fig. 4a) but also in epithelial cells of thickened alveoli septae where collagen deposition in the interstitium was evident (Fig. 4b); in contrast, little ZEB1 staining or collagen deposition was observed in alveoli of control lung tissue (Fig. 4c).