Despite Onodera and coworkers finding increased levels of MMP-1 protein in supernatants of MIF-stimulated early passage (passage 3) RA synovial fibroblasts [47], we found no upregulation of MMP-1, MMP-3, and MMP-13 by MIF in later passage (passage 8) cells. Here, MMP13 is linked to rheumatoid arthritis.