MMP9 and rheumatoid arthritis: In addition, MMP-1, MMP-2, MMP-9, and MMP-13 are closely related to the expression of RA-FLS and VEGF [9, 10], but there are relatively few studies on the correlation between MMP-1, MMP-3, and VEGF, while MMP-1 and MMP-3 are closely related to the bone destruction of RA joints [11].