We established the first comprehensive map of HDAC3 DNA occupancy in dependence of proteasome inhibitors in multiple myeloma cells and identified the histone deacetylase HDAC3 as a candidate protein that is either directly or indirectly (i.e., through a recruiting factor because the enzyme is lacking a DNA binding domain) targeted by the proteasome in a site-specific manner. The gene discussed is HDAC3; the disease is plasma cell myeloma.