Fig. 6. Ptc¹⁴ activates the Hh pathway only in the absence of Hh. (A-D) The upregulation of Ptc (A) and Col (C) expression (green) at the AP compartment border observed in a wild-type wing disc is not produced in ptc¹⁴ clones (shown by the lack of ß-gal staining, red) in an hh^ts2 disc after 30 hours at the restrictive temperature (B,D; arrowheads). Of 20 clones in the A compartment with A sister clones, eight were touching the AP compartment border and did not showed activation of Ptc or Col at the restrictive temperature. (E) Cuticle preparation of wild-type, ptc¹⁴ and ptc¹⁴; hh^ts2 embryos at the restrictive temperature. Note that the double mutant ptc¹⁴; hh^ts2 embryo is like an hh^- embryo, and not like a ptc^- embryo, which would normally be the case with ptc^-; hh^- double mutant embryos. (F) Wg expression pattern in wild-type, ptc¹⁴ and ptc¹⁴; hh^ts2 embryos at the restrictive temperature. In the ptc¹⁴ embryo, Wg stripes are broadened compared with the wild-type embryo, but Wg is not expressed in ptc¹⁴; hh^ts2 embryos at the restrictive temperature. Scale bars: 50 µm.