MUC1 and rheumatoid arthritis: Lastly, in terms of the survival analysis, the KL-6 level in death of ILD was 383.53 (U/ml) higher than in survivors of ILD (Figure 4), and highlighted that elevated KL-6 could be a prognostic marker to effectively indicate the survivor in rheumatoid arthritis-associated interstitial lung disease (RA-ILD), as well as in idiopathic pulmonary fibrosis (IPF) (Supplementary Figure 2).