Indeed, levels of MMP-2 and MMP-9 protein and MMP7 mRNA are elevated in the lungs of patients with human idiopathic pulmonary fibrosis (IPF) [28]–[30] and MMP-13 expression is increased in the lungs of patients with chronic obstructive pulmonary disease (COPD) [31]. Here, MMP9 is linked to idiopathic pulmonary fibrosis.