TNF and rheumatoid arthritis: Pro-inflammatory mediators contained with IL-1β, TNF-α, and PGE2 can also enhance the binding activity of NF-κB with Nurr1 promoter, thereby promoting Nurr1 transcription and elevating Nurr1 mRNA and protein level in primary rheumatoid arthritis and normal synoviocytes (McEvoy et al., 2002).