Fig. 6. ptc^- en^- clones in flies lacking one or both systems. (A-C) The Hh signal transduction pathway is maximally and constitutively activated in ptc^- en^- clones. Such clones reverse the polarity of hairs behind the clone both in ds^- flies (A) and in stan^- flies (C). However in ds^- stan^- flies, the ptc^- en^- have no discernable (consistent) effect on the surround (B) compared with A where there is a consistent effect: the hairs pointing inwards all around the clone. Clones marked with pwn. Anterior is towards the top, red lines outline the clone and red arrows indicate the polarity imposed on cells outside the clone.