msh specifies dorsal cell fate in the Drosophila wing

Drosophila limbs develop from imaginal discs that are subdivided into compa rtments. Dorsal-ventral subdivision of the wing imaginal disc depends on ap terous activity in dorsal cells. Apterous protein is expressed in dorsal ce lls and is responsible for (1) induction of a signaling center along the do rsal-ventral compartment boundary (2) establishment of a lineage restrictio n boundary between compartments and (3) specification of dorsal cell fate. Here, we report that the homeobox gene msh (muscle segment homeobox) acts d ownstream of apterous to confer dorsal identity in wing development.