Fig. 8. SmoC requires endogenous Smo to activate signaling. Clones of wing cells lacking endogenous smo activity were generated using the FLP;FRT system and marked by loss of GFP. Iro (red) was lost in the L3 region (arrows) when smo was removed (A). Expression of UasSmoC/+ under control of hemizygous MS1096 (e.g. 2x SmoC) did not rescue Iro expression in clones of cells lacking endogenous smo (arrows in B). Adult brothers of the larvae used in B had significant ectopic venation, demonstrating that the expression level of SmoC was sufficient for significant activity in the presence of endogenous Smo.