HDAC9 and neoplasm: Altered HAT and HDAC activity has been identified in several types of cancer (Cress and Seto, 2000; Mahlknecht and Hoelzer, 2000; Timmermann et al, 2001), and a number of HDAC inhibitors have been characterised that inhibit tumour growth in vitro and in vivo (Marks et al, 2000a, 2000b; Takai et al, 2004).