MUC1 and idiopathic pulmonary fibrosis: Among the UIP group, the low KL-6 group (<780 U/mL, n = 12) also showed better prognosis (median survival period: not reached vs. 27 months, P = 0.001) than the high KL-6 group (≥780 U/mL, n = 18) (Fig 1B).