UASt regulatory sequences drive expression of HDAC4 that carries amino acid substitutions S239A, S573A and S748A (mutation of the equivalent residues in the orthologous human gene has previously been shown to result in nuclear retention of the protein) and in which the Mef2 binding site has also been mutated (amino acid substitutions K165A, L168A and I172A). The coding sequence is tagged at the C-terminal end with 6xTag:MYC.