MMP3 and rheumatoid arthritis: As shown in Figure 1, the percentage of MMP3+ lining cells in RA patients (median 47%, IQR 39~52%) was significantly higher than that in OA (median 19%, IQR 15~24%, P < 0.001) or in OrthA patients (median 7%, IQR 0~24%, P < 0.001).