(A) Schematic diagram of wing disc, where UAS constructs are expressed with apgal4 (green) and LexOV5Pent from the dpp stripe (dppLexA). (B–F) Third instar wing discs expressing UASGFP (B), UASDallyGFP (C), UASDally△HSGFP (D), UASDlpGFP (E) or UASTkvGFP (F) with apGal4, immuno-stained for V5Pent which is expressed in the Dpp stripe. V5Pent accumulates on cells expressing Dally or Dlp. (G) Third instar wing disc with clones mutant for Dally and Dlp (marked by dashed line), stained for Pent. Endogenous Pent does not accumulate in the mutant clones. (H–J) Third instar wing discs expressing UASDallyGFP (H), UASDlpGFP (I) or UASTkvGFP (J) with apGal4 immunostained for Pent. Pent accumulates on cells expressing Dally or Dlp, but not Tkv. (K–L) Control PentYFP wing disc (K) and disc expressing VHH-GFP4::CD8::mCherry, a chimeric membrane protein comprising an extracellular, single domain anti-GFP nanobody and cytoplasmic mCherry under control of dppGal4 (L). In control discs, PentYFP is mostly found in the lateral region of the disc, whereas Pent is seen at high levels in the centre of the disc when the nanotrap is expressed, demonstrating that Pent spreads far from the lateral regions of the disc. Scale bars are 50 µm in all images.