Fig. 3.

Canonical Wnt pathway activation triggers morphological changes in APC null clones. Late 3^rd larval instar wing discs. Clones expressing stabilized Arm (UAS-Arm^S10-Myc; A–C’), and axin null clones (D, D’) closely resemble APC null clones by exhibiting apical constriction (A, A’) invagination/evagination (B, arrows indicate apical surface of invaginated clones; C–D’), and smooth borders (A–D’). Dotted lines indicate clone borders (based on Myc expression). (A’) Close-up of the area in the rectangle in A. (E–E2) The APC null phenotype is suppressed in APC null clones in the posterior compartment expressing TCF^ΔN and GFP driven by engrailed-GAL4 using mosaic analysis with a repressible cell marker (MARCM). While APC null clones in the posterior compartment express both GFP and TCF^ΔN, APC null clones in the anterior compartment do not express either GFP or TCF^ΔN (E, arrows). In the anterior compartment, clone boundaries were determined by loss of APC2 (not shown). (E1, E2) Close-ups of areas in rectangles in E’. (F) Quantification of average apical cell surface area ratios of indicated genotypes (ratio = average area per cell in clone cells/average area per cell in neighboring cells). Scale bars: 10 µm.