FOXJ1 and idiopathic pulmonary fibrosis: Figure 1A,B show a healthy epithelium in terminal bronchioles consisting of basal cells (KRT5+, red) and ciliated cells (FOXJ1+, yellow) in a pseudostratified layer. Similar epithelial layers were identified in the IPF samples, together with typical pathological features of IPF such as honeycomb cysts. These were lined with epithelial cells positively stained for FOXJ1 and KRT5 (Figure 1G–I). This staining pattern was also observed in pulmonary areas of suspected bronchiolization (Figure 1K–N).