HDAC6 (UniProt/Swiss-Prot entry Q9UBN7) belongs to class II of the histone deacetylase family. These enzymes catalyse the deacetylation of lysine residues on the N-terminal part of the core histones (H2A, H2B, H3 and H4). Histone deacetylation plays an important role in transcriptional regulation, cell cycle progression and developmental events. HDAC6 also plays a key role in the degradation of misfolded proteins and in microtubuledependent cell motility via deacetylation of tubulin and is involved in the MTA1-mediated epigenetic regulation of ESR1 expression in breast cancer.