KRT5 and idiopathic pulmonary fibrosis: In several fibroblast foci from all examined IPF blocks, KRT17+/KRT5+ cells containing intracellular collagen VII were found in the intermediate epithelial layer, surrounded by negative luminal epithelial cells above and pathologic fibroblasts below, often with an impaired integrity of collagen VII in the basement membrane zone underneath (Figure 6, G–I, and Supplemental Figure S9).