For example, coupled acetylation/deacetylation reactions, carried out by histone acetyltransferases and histone deacetylases (HDAC), respectively, are widespread within eukaryotes and act as regulators of numerous cellular events.7,8 Aberrant HDAC activity has been associated with a number of different diseases and enzyme inhibitors have broad therapeutic potential.9,10 This is particularly the case with cancer, where anti-proliferative effects can result from induction of cell cycle arrest and apoptosis.11 Here, HDAC9 is linked to cancer.