MUC1 and idiopathic pulmonary fibrosis: Higher levels of KL-6 in IPF and NSIP patients than controls but no difference between IPF and NSIP patientsIPF patients: positive correlation between KL-6 levels and basal FiO2 and negative correlation with distance of 6-min walking testNSIP patients: negative correlations between KL-6 levels and FVC baseline, a distance of 6-min walking test, and final SpO2