Fig. 8. Signaling activity of Hh-GFP, HhN-GFP and Hhc85s-GFP in cells lacking tout-velu function and simultaneously expressing Hh. (A-D) Wing imaginal discs with clones mutant for ttv that also express wild-type Hh ectopically. All clones in the anterior compartment shown in the figure are located outside the expression domain of the different target genes tested. Clones are marked with GFP (A-D) and outlined with a red line (A'-D'). The discs are stained for different Hh targets (red): En (A,A'), Ptc (B,B'), Iro (C,C') and Ci (D,D'). (E) The results of the clone analysis. Hh triggers the response of low-threshold responses (Ci and Iro) in ttv^- cells, while failing to activate high-threshold response genes (Ptc, En and Col) apart from the first row of cells within the clone.