CALD1 and idiopathic pulmonary fibrosis: Notably, the fold increase in POSTN expression observed in the lung tissue of IPF patients exceeds the level verified in the fibroblast model test. In further immunohistochemical analysis (Figure 5D), protein expression levels of CALD1, CDH2, and POSTN were significantly elevated at the histological level in IPF patients, a finding substantiated by quantitative results (Figure 5E, n=8 for each group) .