Plays a key role in the specification of proneural and promuscular cluster formation (PubMed:8887329, PubMed:9486795). Required for the specification of dorsal and lateral muscle progenitor cells (PubMed:8887329, PubMed:9486795). Regulates development of peripheral nervous system derived from lateral neuroblasts (PubMed:28716930). Dorsal lateral ectoderm, developing central and peripheral nervous systems and the somatic mesoderm. Expressed in dorsal and lateral muscle preclusters and mesodermal fat body precursors. Embryo, between 4 hours and larval first instar whereupon expression is greatly reduced. Continued expression only in the CNS up until hatching. Belongs to the Msh homeobox family.