Proximal distal axis formation in the Drosophila leg: distinct functions of Teashirt and Homothorax in the proximal leg

The proximal distal axis of the Drosophila leg is patterned by expression of a number of transcription factors in discrete domains along the axis. The homeodomain protein Homothorax and the zinc-finger protein Teashirt are broadly coexpressed in the presumptive body wall and proximal leg segments. Homothorax has been implicated in forming a boundary between proximal and distal segments of the leg. We present evidence that Teashirt is required for the formation of proximal leg segments, but has no role in boundary formation.