HDAC3 and rheumatoid arthritis: We manipulated HDAC3 activity using propionate or another HDACs inhibitor Trichostatin A (TSA).56 TSA increased acetylation of FOXK1 (Fig. 5q) and reduced protein levels of FOXK1 and key mediators of interferon signaling (STAT1 and STAT2) in RA-FLSs in a concentration-dependent manner (Fig. S7).