In IPF patients, induced sputum KL-6 levels showed strong negative correlations with multiple lung function indices, including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and diffusing capacity for carbon monoxide (DLCO) (all p<0.05), and a strong positive correlation with HRCT scores (r=0.908, p<0.001). Here, MUC1 is linked to idiopathic pulmonary fibrosis.