DNA-Binding Proteins/physiology; Gene Expression Regulation; Myosin Heavy Chains/metabolism; Serum Response Factor/metabolism; Transcription Factors/physiology; Animals; Base Sequence; Binding Sites; Cells, Cultured; DNA-Binding Proteins/metabolism; Gene Deletion; Green Fluorescent Proteins/metabolism; Luciferases/metabolism; MEF2 Transcription Factors; Mice; Molecular Sequence Data; Muscle, Skeletal/enzymology; Mutation; Myocardium/enzymology; Myogenic Regulatory Factors; Octamer Transcription Factor-1; Oligonucleotides/chemistry; Plasmids/metabolism; Promoter Regions, Genetic; Protein Binding; Protein Isoforms; Protein Structure, Tertiary; Tissue Distribution; Transcription Factors/metabolism; Transcription, Genetic; Transcriptional Activation; Transfection