In a further step, we disclosed that a 5-biomarker signature consisting of MMP-3, MMP-7, MMP-9, MMP-10, and TIMP-1 effectively better-characterized RA-ILD+versus IPF compared to when independently assessed, yielding an AUC of 0.8836 (Fig. 5C). The gene discussed is MMP9; the disease is idiopathic pulmonary fibrosis.