Given that the doses of ACY-241 used in this study demonstrated pharmacodynamic regulation of both HDAC6 and Class I HDACs, future studies exploring the role(s) of specific HDAC isozymes in the regulation of Myc and survivin expression will be important to further define the mechanism of action of selective HDAC inhibitors in this combination in models of MM. This evidence concerns the gene HDAC9 and Miyoshi myopathy.