HDAC9 and B-cell non-Hodgkin lymphoma: HDAC inhibitors, valproic acid and romidepsin, can transactivate the CD20 gene via promoter hyperacetylation and Sp1 recruitment (Shimizu et al., 2010); therefore, both HDAC inhibitors increase CD20 expression in B-cell lymphoma lines and reduce the growth of B-cell lymphomas synergistically with anti-CD20 monoclonal antibodies.