Wing imaginal discs from third instar D. melanogaster larvae harbouring the following transgenes: (a) hh-Gal4, UAS-ds and ex-lacZ; (b) hh-Gal4, UAS-ds, UAS-riqRi and ex-lacZ; (c) hh-Gal4, UAS-ds, UAS-mnbRi and ex-lacZ; (d) hh-Gal4, UAS-ftΔICD and ex-lacZ; (e) hh-Gal4, UAS-ftΔICD, UAS-riqRi and ex-lacZ. Yki activity was reported by ex-lacZ levels (grey in a-e). Cubitus interruptus (Ci) expression (red in a’-e’) marked the anterior compartment of wing imaginal discs. Merged images are shown in (a’’-e’’). X-Z sections through the wing pouch are shown below planar sections of wing discs in a-c”. (f) Levels of ex mRNA and Diap1 mRNA relative to the control actin5C mRNA, assessed by QRT-PCR, in wing imaginal discs harbouring the following transgenes: 32B-Gal4 and UAS-ftΔICD; and 32B-Gal4, UAS-ftΔICD and UAS-riqRi. Data is presented as mean ± SEM, n=3, ** = p<0.01.