TRAF6 and rheumatoid arthritis: However, the role of TRAF6 may be pro-inflammatory in some circumstances since a small molecule inhibitor, C25-140, that disrupts binding of TRAF6 to its partner E2 ligase Ubc13, results in decreased TCR-induced activation of NF-κB and decreased psoriasis and rheumatoid arthritis in murine models [79].