YY1 and rheumatoid arthritis: After RA-FLS were treated with 10 ng/ml TNFα for 48 h, both the expression of HMGB1 (Fig. 5a) and YY1 (Fig. 5b) and IL-6 production (Fig. 5c) were significantly increased compared with the control-treated RA-FLS, and the expression of miR-449a was decreased(Fig. 5d).