Previously, the level of Collagen type III breakdown product in the urine (uC3M), measured by ELISA for the MMP-9 generated neo-epitope of Collagen type III, was described as a non-invasive biomarker of fibrosis in several models of renal fibrosis (5/6 Nx, anti-Thy 1.1, and adenine nephropathy models) [29]. Here, MMP9 is linked to renal fibrosis.