Fig. 1. Dpp morphogen gradients and expression of Dpp signaling components in the developing wing. (A,B) Patterns of Dpp-GFP expressed in A/P border cells by dpp-GAL4 driver (A; dpp^d12/+; dpp-GAL4/UAS-Dpp-GFP) and Dpp activity gradient visualized by anti-pMad antibody staining (B). (C,D) Expression patterns of the Dpp type I receptor gene tkv (C) and a putative Dpp co-receptor gene dally (D), were followed by anti-ß-galactosidase antibody staining of wing discs of the enhancer trap lines tkv^P906 and dally^P2, respectively. Brackets show positions of the A/P border cells. Posterior is towards the right and ventral is towards the top of all wing discs and in all subsequent figures.