MUC1 and idiopathic interstitial pneumonia: We retrospectively investigated the immunohistochemical expression of SP-A, KL-6, cytokeratin (CK), and epithelial membrane antigen (EMA) in alveolar epithelial cells in lung tissues obtained from surgical lung biopsy in 43 patients with IIPs, and analyzed the correlation between expression of these markers and the prognosis of each IIP patient.