Opposing interactions between homothorax and Lobe define the ventral eye margin of Drosophila eye

► We study the genetic mechanism involved in generation of head versus eye boundary during organogenesis in flies. ► homothorax (hth) acts antagonistically to the Lobe (L, PRAS40 homolog) in the ventral eye. ► L interacts with alternative spliced variant of Hth that encodes Meis-Hth (MH) domain. ► Optimum level of L and hth define boundary between eye and the head cuticle on ventral margin. ► Extradenticle (Exd) is not a critical rate limiting factor in L and Hth interaction.