MUC1 and idiopathic pulmonary fibrosis: These include serum biomarkers (KL-6, SP-D, MMP-7), bronchoalveolar lavage fluid biomarkers (SP-D, KL-6, MMP-7), exhaled breath condensate biomarkers (hydrogen peroxide, nitric oxide, leukotrienes), lung tissue biomarkers (studied for IPF diagnosis but requiring invasive procedures), genetic biomarkers (such as MUC5B, telomere length), proteomic biomarkers (SAA, AAT), metabolomic biomarkers (sphingolipids, glycerophospholipids), and microRNA biomarkers (miR-21, miR-155).