Dpp from the anterior stripe of cells is crucial for the growth of the Drosophila wing disc.

The Dpp morphogen gradient derived from the anterior stripe of cells is thought to control growth and patterning of the Drosophila wing disc. However, the spatial-temporal requirement of dpp for growth and patterning remained largely unknown. Recently, two studies re-addressed this question. By generating a conditional null allele, one study proposed that the dpp stripe is critical for patterning but not for growth (Akiyama and Gibson, 2015). In contrast, using a membrane-anchored nanobody to trap Dpp, the other study proposed that Dpp dispersal from the stripe is required for patterning and also for medial wing disc growth, at least in the posterior compartment (Harmansa et al., 2015). Thus, growth control by the Dpp morphogen gradient remains under debate. Here, by removing dpp from the stripe at different time points, we show that the dpp stripe source is indeed required for wing disc growth, also during third instar larval stages.