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Fig. 5. Effects of loss of function of Notch and shaggy on the stability of Armadillo. (A,D,G,J) GFP, green; (B,E,H,K) endogenous Armadillo, red; (C,F,I,L) merge of GFP and Armadillo images. (A-C) Loss of function of shaggy (loss of GFP) results in a cell autonomous elevation of the levels of Armadillo, which remains largely associated with adherens junctions (inset C, apical is up). Notice that only clones of a certain size (> about five cells) show the elevated levels of Armadillo (arrowheads in A,B); this is probably due to the long perdurance of Shaggy. The epithelium looks very thick (compare to inset F) because the loss of shaggy affects the epithelial organisation of the cells (A.M.A., unpublished data). (D-F) Simultaneous loss of Notch and shaggy results in very elevated levels of Armadillo that appear delocalised within the cytoplasm (inset F). The clones are small. Loss of Notch function affects cell proliferation (de Celis and Garcia-Bellido, 1994). (G-I) Expression of wild-type Armadillo under the control of ptcGal4 results in a Wingless-dependent stabilisation of Armadillo (see also Fig. S3 and Fig. S4 in supplementary material) in a narrow band at the AP border and, in particular, at the intersection with the dorsoventral boundary (arrowhead in H) where levels of Wingless are highest. Clones of wild-type cells (loss of GFP) do not change the instability of the ectopic Armadillo (dots indicate regions in clones where Armadillo has not accumulated). (J-L) Wing disc heterozygous for Notch (Df(1)N^81k/+). The ptcGal4-driven expression of Armadillo is broader and contains more cells maintaining higher levels of Armadillo than in wild type. Furthermore, within the Notch mutant clones an increased number of cells have high levels of Armadillo (compare with G-I). Notice some clones, that lie far from that AP boundary (arrowhead in J-L) maintain high levels of Armadillo. N.B. In general we do not observe changes in the levels of Armadillo as a result of loss of Notch function alone, but in some experiments we observe an elevation in the levels of Armadillo. This elevation is always observed in the neighbourhood of the DV boundary (A.M.A., unpublished data). Unfortunately this effect is not reproducible and therefore should remain anecdotal.

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