MUC1 and idiopathic pulmonary fibrosis: Among patients with IPF with serial KL-6 data (n = 77), changes in KL-6 levels over 1 month tended to be higher in the DP group ([absolute] 99.0 vs. − 23.2 U/mL, p = 0.027; [relative] 7.4 vs. − 0.9%, p = 0.073) than those in the no-DP group (Fig. 2A).