Fig. 5. Ectopic Egfr signalling transforms the identity and cell morphology of the PE into notum. (A) vn-expressing clones (green) transform the cell morphology of peripodial cells in a incompletely penetrant way (asterisk in a region of the clone not transformed). The transformation affects cells outside the clone (arrowhead). Ubx expression is repressed in some regions of the clone. (B) Expression of the constitutive Egfr activator Ras^V12 (clones in green) transforms both cell autonomously and non-autonomously squamous peripodial cells into columnar cells, as seen both in a surface view and a longitudinal section (s1). Arm (red) and TO-PRO-3 (blue) staining reveal cell shape and tissue structure (apical membranes of both sides of the disc separated by a broken line). (C) Ras^V12-expressing clones eliminate Ubx expression (red) in transformed cells inside, but not outside the clone (inset at higher magnification of the outlined clone). An asterisk marks the region of non-autonomous transformation, not fully penetrant around the clone. The arrowhead indicates a clone in the wing-notum side that does not affect apposed squamous cells. (D) iro-C is induced autonomously by Ras^V12 expression in peripodial cells (longitudinal section s2 of the outlined clone). Asterisk indicates a clone in the wing-notum side of the disc that does not affect apposed squamous cells. (E) Ras^V12 induces expression of iro-C in distal cubic cells (inset at higher magnification of the outlined clone). The clones in all panels were generated 48-72 hours AEL.