MMP1 and idiopathic pulmonary fibrosis: MMP13, also known as collagenase 3, is the principal interstitial collagenase and has a high specificity for degrading insoluble fibrillar collagens, especially type II and I. MMP13 was shown to be significantly upregulated at the mRNA and protein level in IPF lungs in a study where 16 patients were enrolled [115].