DNA-Binding Proteins/metabolism; Myopathies, Structural, Congenital/enzymology; Myopathies, Structural, Congenital/genetics; Protein Serine-Threonine Kinases/deficiency; Transcription Factors/metabolism; Amino Acid Sequence; Animals; Base Sequence; DNA/genetics; DNA-Binding Proteins/deficiency; DNA-Binding Proteins/genetics; Enhancer Elements, Genetic; Gene Expression Profiling; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; MEF2 Transcription Factors; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Molecular Sequence Data; Muscle, Skeletal/embryology; Muscle, Skeletal/enzymology; Muscle, Skeletal/pathology; Myogenic Regulatory Factors; Myopathies, Structural, Congenital/etiology; Myopathies, Structural, Congenital/pathology; Protein Serine-Threonine Kinases/genetics; Protein Serine-Threonine Kinases/metabolism; Signal Transduction; Transcription Factors/deficiency; Transcription Factors/genetics; Transcription, Genetic