MMP9 and rheumatoid arthritis: After 60-μM artesunate treatment for 24 h, the expression of MMP-2 and MMP-9 in the primary RA-FLS culture supernatant were significantly decreased (MMP-2: P = 0.021, MMP-9: P = 0.006), whereas other MMPs including MMP-1 and MMP-3 remained the same (all P > 0.05).