Arginine codons 243 (CGG) and 247 (CGA) in exon 4 were changed to alanine (GCA) (p.R243A, p.R247A) and an FRT site flanked neomycin resistance gene cassette was inserted into intron 4. The neo cassette was removed through subsequent flp-mediated recombination. The mutated arginine residues are essential for binding to the Hdac1 protein but their mutation doesn't affect other binding properties. (J:310648)