Cell permeable, potent and selective class IIb HDAC6 inhibitor (IC50 =5nM). Displays high selectivity over all other HDACs (IC50=0.2-11µM). Induces cellular alpha-tubulin, but not histone H3 hyperacetylation in Neuro-2a cells. Promotes mitochondrial transport. Shows improved kinetics and biochemical potency against HDAC6 compared to tubastatin A (AG-CR1-3900). HDAC6 deacetylates tubulin, HSP90 and the core histones (H2A, H2B, H3, H4). Histone deacetylases act via the formation of large multiprotein complexes. HDAC6 plays an important role in microtubule-dependent cell motility, transcriptional regulation, degradation of misfolded proteins and cell cycle and is involved in autophagy, inflammation, cancer and neurodegeneration.