MMP9 and rheumatoid arthritis: Studies (54, 55) have shown that the anti-RA effect of baicalin is related to the down-regulation of pro-inflammatory factors (TNF-α, IL-1β, and IL-6) and inflammatory markers (MMP-2, MMP-9, iNOS, and COX-2), the induction of monocyte apoptosis in synovial fluid of CIA mice, and the inhibition of JAK1/STAT3 and TLR2/MYD88/NF-κB p65 signal transduction.