Figure 4

scrib mutant wing disc tissue overgrows through impaired Hippo signaling. Confocal sections through 3^rd instar larval wing discs (A-H), posterior to the left. en-GAL4 driven expression of transgenes in the posterior half of the discs (A-D) is marked by GFP expression (green, or magenta in the merges). Grayscale is β-GAL (A-D) or F-actin (E-H). (A-D) en-GAL4 driven expression of scrib^RNAi in the posterior half of the wing disc increases ex-lacZ (A), fj-lacZ (B) and msn-lacZ (C) expression. Coexpression of bsk^DN with scrib^RNAi does not rescue the increased expression of fj-lacZ (D). (E-H) scrib¹/scrib³ transheterozygous mutant wing discs over grow and become increasingly disorganized (E). Halving the gene dosage of yki dramatically reduces the size of homozygous scrib mutant wing discs (F). In contrast, neither halving the gene dosage of Ras85D (G) or bsk (H) reduces homozygous scrib mutant wing disc overgrowth.