MMP15 and idiopathic pulmonary fibrosis: In particular, MMP15 (membrane-type 2 MMP) is known to be upregulated by HIF-1α under hypoxic conditions [73,74] and is expressed in alveolar epithelial cells in Idiopathic Pulmonary Fibrosis (IPF) [75], an Interstitial Lung Disease (ILD) characterized by chronic inflammation, progressive formation of scar tissue and decreased lung function.