In the acute disease phase immediately following CFA induction, the Mmp12–/– MRL/lpr mice displayed a faster onset of arthritis that was detectable at day 6 by significant and more severe ankle swelling than Mmp12+/+ MRL/lpr mice, that continued to exacerbate to day 25 (Fig. 5e). This evidence concerns the gene MMP12 and arthritic joint disease.