SIAH2 and plasma cell myeloma: Moreover, we found that SIAH2, a ubiquitin ligase that mediates proteasomal degradation of HDAC3 and its recruiting factor NCOR1 (47, 49), colocalizes with the deacetylase, increases acetylation of c-MYC- and HDAC3-controlled genes, and enhances the oncogenic potential of multiple myeloma cells.