play an important role in the modification of chromatin structure and thus in the suppression and activation of transcription and cellular differentiation. There are 11 members in the HDAC family that are classified into four classes. Class I HDACs represent homologs of the yeast histone deacetylase RPD3, class II HDACs share strong homology with the yeast histone deacetylase HDA1, class III HDAC are closely related to the yeast SIR2 protein, and class IV HDACs comprises Histone deacetylase 11 (HDAC11)-related enzymes. HDAC11 contains 347 amino acid residues.