Fig. 5. spen is required for Wg signaling in the wing imaginal disc. (A-C) Confocal images of third instar wing imaginal discs containing randomly generated spen^XIE1796 clones (marked by the absence of GFP, boundary shown by white lines). Samples were stained for Sens (A) and Wg (B); the merged image is shown (C). Reduction or total lack of Sens (A) was observed in some spen clones (spen^9C7: 23% and 26%, respectively, n=31; spen^14C2: 50% and 6.7%, n=30; spen³: 27% and 0%, n=30; spen^XIE1796: 30% and 8.6%, n=70), and Wg level is unaffected or slightly derepressed (B), consistent with attenuated Wg signaling in cells that lack spen. (D-G) Confocal images of third instar wing imaginal discs containing the transgenes P[en-Gal4] and P[UAS-spen^DN]^II stained for Sens (D,F), Wg (E) and Fz2 (DFz2 in figure) (G). Flies were reared at 18°C. Expression from P[UAS-spen^DN] in the posterior compartment of the wing reduces (D) or eliminates (F) Sens expression (the posterior compartment is towards the right of the arrows in F and G; 44% are similar to D, 27% are more severe but some Sens remains and 29% are as in F, n=68) and derepresses Wg (E, 97%, n=31). By contrast, expression of Fz2 is either unaffected (compare arrowheads; G, 73%, n=45) or reduced throughout the posteior compartment (data not shown, 27%).