C25-140 is a specific, first-in-class small molecule inhibitor of the TRAF6-Ubc13 interaction, binds TRAF6, inhibits TRAF6-Ubc13 interaction and TRAF6 activity.

DI-591 (DI591) is a potent, selective, cell-permeable inhibitor of the DCN1-UBC12 interaction with Ki of 10-12 nM for human DCN1 and DCN2.

NSC697923 is a selective inhibitor of Ubc13-Uev1A

TZ9 is a novel inhibitor of Rad6 ubiquitin conjugating enzyme(E2 enzyme); inhibits MDA-MB-231 cell proliferation with IC50 of ~6 uM.