Fig 1. A phenotypic series for α-Cat reveals distinct roles in growth regulation and epithelial polarity.

(A) Schematic of 3^rd larval instar wing imaginal disc. Indicated are the main subdivisions of the disc proper, the compartment boundaries (AC, anterior compartment; PC posterior compartment; DC, dorsal compartment; VC, ventral compartment), the expression domains of the en-Gal4 and omb-Gal4 drivers used in this study, and the area of the discs shown in (B). (B) Late 3^rd larval instar wing discs with control (left two panels) or α-Cat¹ null mutant clones positively labeled with GFP. In contrast to control clones, α-Cat¹ mutant clones are not observed. When cell death is suppressed through expression of p35, α-Cat¹ mutant cells are found basal to the epithelium and show extensive protrusive activity (arrowheads in close-ups). Scale bar, 25 μm. (C) KD of α-Cat in the PC (marked by RFP) with α-Cat-RNAi(1) causes tissue overgrowth, whereas KD of α-Cat in the PC with α-Cat-RNAi(1) in the presence of one copy of α-Cat¹ causes a degeneration of the PC. Scale bar, 100 μm. (D) KD of α-Cat in the PC (marked by RFP) with α-Cat-RNAi(1) while expressing p35 causes tissue overgrowth, whereas KD of α-Cat in the PC with α-Cat-RNAi(1) while expressing p35 in the presence of one copy of α-Cat¹ causes the formation of a multilayered tumor mass with small epithelial vesicles or patches. Apical domain of epithelial cells marked by enrichment of F-actin and Crb. Scale bars, 100 μm. (E) Quantification of wing disc area in flies of indicated genotypes. Two-tailed, unpaired t-test used to determine statistical significance. ns (P>0.05), ****(P≤0.0001).