Plays a role in cell differentiation late in myogenesis. Transcription factor Mef2 is essential for expression. In the embryo, expression is restricted to the somatic, visceral, and pharyngeal muscles. Within the somatic musculature, expression is localized at the ends of muscles fibers at the point of attachment to the epidermis (at protein level). There is no expression in cardiac mesoderm or in fat body. Expression is biphasic, peaking late in embryogenesis (16-24 hours embryos) and during the larval to pupal transition, when the musculature is differentiating. Found in developing muscles of the visceral and somatic mesoderm subsequent to the formation of the muscle precursor cells. Decreased levels are still detectable in adults.