Transcriptional activator which binds specifically to the MEF2 element, 5'-YTA[AT](4)TAR-3', found in numerous muscle-specific genes. Activates transcription via this element. May be involved in muscle-specific and/or growth factor-related transcription. Interacts with HDAC7 (By similarity). Heterodimer. Interacts with HDAC9. Expressed in skeletal and cardiac muscle and brain. Belongs to the MEF2 family.