UBE2O and plasma cell myeloma: Furthermore, UBE2O has been found to be downregulated in MM cells, and the restoration of UBE2O levels and activity induces MM cell apoptosis and suppresses cell proliferation both in vitro and in vivo, suggesting that UBE2O acts as a tumor suppressor against MM and might therefore be a potential therapeutic strategy for the treatment of multiple myeloma (Figure 2C) [62].