Fig 3. Up-regulation of Cos2 in ubr3 mutant clones is responsible for the loss of Hh signaling.

(A-A’) ubr3^B mutant cells (marked by GFP) up-regulate Cos2 (red; arrows). (B-B’) Over-expression of Cos2 by eyg-Gal4 (indicated by expression of GFP) leads to loss of Ci¹⁵⁵ (arrow in B’) at the morphogenetic furrow. (C-C’) Over-expression of Cul1 by eyg-Gal4 (indicated by expression of GFP) does not cause loss of Ci¹⁵⁵ at the morphogenetic furrow. (D-D’) Down-regulation of Cos2 by over-expression of cos2^RNAi in ubr3^B mutant clones (marked by the expression of GFP) suppresses loss of Ci¹⁵⁵ (red) in the morphogenetic furrow (arrows in D’). (E-E’) Down-regulation of Cul1 by over-expression of cul1^RNAi in ubr3^B mutant clones induces ectopic activation of Hh signaling anterior to the morphogenetic furrow (shown by expression of Ci¹⁵⁵, arrow) but does not rescue Ci¹⁵⁵ loss in the morphogenetic furrow (arrowheads). (F-F’) Over-expression of ptc^DN in ubr3^B mutant clones does not rescue Ci¹⁵⁵ loss in the morphogenetic furrow (arrowhead).