MMP3 and rheumatoid arthritis: The results of this study show that suppression of PGC-1β attenuates the expression of TNF-α, IL-6, IL-8, MMP-3, MMP-13 and RANKL, and enhances apoptosis through inhibition of p38, ERK and NF-κB activation in RA-FLS, which suggests that blocking PGC-1β expression may provide a novel target for the treatment of RA.