IHC labeling for Cldn10 using IPF and COPD lung sections revealed that the columnar club cells that form an organized bronchiolar structure often express Cldn10 either at the lateral membrane between adjacent cells or at luminal end of the cells (Figure 2B, C & L) while non-columnar or cuboidal club cells, which often form disorganized spatial arrangement in mainly IPF lungs, apparently express Cldn10 in cytoplasm and/or nucleus (Figure 2A, D, G & O). The gene discussed is CLDN10; the disease is idiopathic pulmonary fibrosis.