MUC1 and idiopathic pulmonary fibrosis: A study of 14 patients with rapidly progressive IPF by Yokoyama et al. also demonstrated that KL-6 levels in patients who survived (n = 8) significantly decreased from 2661 ± 1178 U/mL to 2160 ± 910 U/mL (P < 0.05) at 1 week and to 1801 ± 899 U/mL (P < 0.05) at 3 weeks after weekly steroid pulse therapy [33].