In 2007, we reported a strong correlation between the expression of 14-3-3η and matrix metalloproteinases (MMPs) and demonstrated that extracellular 14-3-3η possesses MMP-1-inducing activity in vitro on the basis of 14-3-3η levels at the upper range of serum levels observed in a small subset of RA patients [5-7]. Here, MMP1 is linked to rheumatoid arthritis.