MUC1 and idiopathic pulmonary fibrosis: In this context several biomarkers (such as surfactant protein A or SP-A, the Krebs von den Lungen 6 or KL-6, Ig A and periostin [4–8] were studied without much success to be discriminant as early diagnostic biomarkers to identify IPF out of different interstitial lung diseases (ILDs).