Onodera and coworkers showed that MIF-induced MMP-1, MMP-3 and IL-1β mRNA upregulation in RA synovial fibroblasts is inhibited by staurosporine (a broad-spectrum inhibitor of protein kinases such as PKC), a tyrosine kinase inhibitor (genistein), a PKC inhibitor (H-7), and a transcription factor AP-1 inhibitor (curcumin) [47]. Here, MIF is linked to rheumatoid arthritis.