MUC1 and idiopathic pulmonary fibrosis: The ROC curve of BALF and serum KL-6 in the IPF group (Fig. 2), had the area under the curve of 0.89 and 0.73, with power analysis results 99% and 98%, respectively,[41,42] indicating that KL-6 expression in BALF is a good candidate marker for the diagnosis of IPF (P < .05).