In contrast, IPF lung tissue displays loss of alveolar structure, proliferation of interstitial fibrous tissue, a significant increase in CALD1 expression within the cytoplasm of fibroblasts, elevated expression of CDH2 in bronchial epithelial cells and the cytoplasm of fibroblasts, and heightened, brownish-yellow expression of POSTN in proliferating fibrous tissue. This evidence concerns the gene POSTN and idiopathic pulmonary fibrosis.