Fig. 2. Wing size correlates negatively with brk expression. All the discs are doubly stained for GFP and brk (anti-ßgal). The right panels show brk expression in red. For simplification, the labels present only a partial notation of the genotype (see Materials and methods). (A,B) A nub-Gal4>UAS-tkv^QD UAS-GFP disc with a large wing pouch that has little or no brk activity. (C,D) nub-Gal4>UAS-GFP of normal size and normal brk activity. (E,F) The reduction of Dpp pathway activity in nub-Gal4>UAS-tkv^DN UAS-GFP results in a small wing pouch associated with high brk levels. (G,H) Further diminution of Dpp pathway activity in nub-Gal4>UAS-dad UAS-GFP produces a smaller wing pouch associated with an expansion of brk expression that covers the whole of the wing pouch.