NR4A2 is over-expressed in inflamed synovial tissues and cartilage from patients with rheumatoid arthritis (RA), osteoarthritis (OA), and psoriatic arthritis (PsA), and NR4A2 is the most highly expressed member of the NR4A receptor family in these tissues [7-12]. This evidence concerns the gene NR4A2 and rheumatoid arthritis.