MUC1 and interstitial lung disease: Lee et al. [12] confirmed that the elevated serum KL-6 levels in patients with CTD-ILD is positively correlated with computed tomography (CT) grade and negatively correlated with forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO), suggesting that elevated serum KL-6 levels are reflective of the severity of CTD-ILD.