HMGB1 and rheumatoid arthritis: After the transfection of RA-FLS with the miR-NC or cotransfection of RA-FLS with the miR-449a and pCMV-HMGB1 (miR-449a + HMGB1) or pCMV blank vector (miR-449a + HMGB1-NC), cell proliferation, migration, and IL-6 production were detected.