The transgene construct used for the Tg(Myh6-cat)7Rbns and Tg(Myh6-cat)27Rbns alleles was modified to inactivate the Mef2a binding site located at -327..-314 (relative to the transcription start site). Using site-directed mutagenesis, wildtype binding site TTAAAAATAACTGA was changed to TGACCACTCCATGC. (J:4164)