MMP1 and rheumatoid arthritis: These results are in agreement with the extensive work by Sun and Yokota who have shown that lower levels of shear (1–5 dynes/cm2) downregulate MMP-1 expression whereas higher levels of shear (6–20 dynes/cm2) lead to an upregulation of MMP-1 expression in rheumatoid arthritis synoviocytes [33],[39]-[42].