MUC1 and idiopathic pulmonary fibrosis: Serum concentrations of Ca15.3 (I2 = 88.8%, p = 0.001, mean (IPF vs. non-IPF): 91.02 vs. 16.3 U/mL), Ca19-9 (I2 = 97.3%, p < 0.001, mean (IPF vs. non-IPF): 54.71 vs. 15.29 U/mL) and KL-6 (I2 = 91.9%, p < 0.001, mean (IPF vs. non-IPF): 1164 vs. 317 U/mL) were associated with disease progression in IPF patients (Figure 3a–c).