Fig. 5. EXT genes are required for Wg signaling. Dll protein levels in the wild-type and mutant wing discs. (A) Wg is expressed at the wing margin and regulates the Dll expression (gray in the left panel) in a concentration-dependent manner. Schematic diagram is shown on the right panel. (B-D) In botv⁴²³ (B), sotv³²⁶ (C) and ttv⁵²⁴ (D) mutant cells, Dll expression is slightly decreased (arrows). The reduction in Dll protein level is extended to the wild-type cells located on the far side of the mutant clones (C,D).