NR4A2 and rheumatoid arthritis: Consistent with findings that NR4A2 is expressed by macrophage cells in RA ST and in several models of murine autoimmune joint disease, treatment of monocyte and macrophage cells with diverse mediators including lipopolysaccharide (LPS), cytokines, growth factors or oxidized lipids triggers the transcriptional induction of all three NR4A (38, 54).