MMP19 and idiopathic pulmonary fibrosis: Of note, excess matrix accumulation is thought to be an important part in the pathological process of IPF, and its related proteins such as matrix metalloproteinase 1 (MMP1) and matrix metalloproteinase 19 (MMP19) that are strongly upregulated in IPF are proposed to be potential peripheral blood biomarkers [15, 16].