May have a central role in the fusion process during myogenesis, within the somatic mesoderm. Enriched in the embryonic membrane fraction. Expressed in cells of the somatic mesoderm, most notably the muscle founder cells, between embryonic stages 12 and 14, in growing muscle fibers in dorsal, lateral and ventral positions. At stage 16 strongest expression is in some ventral muscles and muscle 8. At stages 16/17 expression is restricted to some cells of the CNS, the brain and the gonads. Expressed both maternally and zygotically. High level of zygotic expression is seen in embryos from stage 12 onwards and in adults. Flies exhibit diminished fusion of embryonic myoblasts to syncytial myotubes.