The formation of longitudinal veins in the Drosophila wing involves cell interactions mediated by the conserved signaling pathways Decapentaplegic (Dpp), Notch, and epidermal growth factor receptor (EGFR). Interactions between Notch and EGFR taking place in the wing disc divide each vein into a central domain, where EGFR is active, and two boundary domains where Notch is active. The expression of decapentaplegic (dpp) is activated in the veins during pupal development, and we have generated Gal4 drivers using the regulatory region that drives dpp expression at this stage. By using these drivers, we studied the relationships between the Notch, EGFR, and Dpp signaling pathways that occur during pupal development. Our results indicate that the interactions between EGFR and Notch initiated in the imaginal disc are maintained throughout pupal development and contribute to determine the places where dpp is expressed. Once dpp expression is initiated, Dpp and EGFR activities in the provein maintain each other and, in cooperation, determine vein cell differentiation.