Because one of the key histological feature of the lung affected with interstitial lung diseases (ILDs) involves injury and/or regeneration of Type II pneumocytes[8], soluble proteins derived from Type II pneumocytes, such as SP-A, SP-D, and Krebs von den Lungen 6 (KL-6), have been studied as potential biomarkers for ILDs[9-15]. The gene discussed is SFTPD; the disease is interstitial lung disease.