MMP1 and rheumatoid arthritis: The ability to cleave the collagen triple helix is unique to the collagenases, and the overexpression of MMP-1 and MMP-13 in chondrocytes in response to proinflammatory cytokines such as interleukin-1-beta (IL-1β) and tumor necrosis factor-alpha is critical in the pathogenesis of OA and RA [1].