TLR4 and rheumatoid arthritis: To explore whether miR-506 targets TLR4, RA-FLSs were co-transfected with the plasmid containing luciferase reporter with either mutant-type (MT) or wild-type (WT) TLR4, and miR-506 mimic or miR-NC and 48 h after transfection, luciferase activity in these cells was estimated.