As shown in Figure 8, periostin expression was most evident at the lateral margin of polyps, which supports the previous finding that periostin in nasal tissues is mainly produced by epithelial cells and deposited into subepithelial regions.25 Periostin expression was also occasionally found in the interstitium of polyp parenchymal tissues, which are rich in myofibroblasts (Figure 8), indicating myofibroblasts and fibroblasts also secrete periostin.26 The gene discussed is POSTN; the disease is polyp.