Fig. 2. Zn fingers 2 and 3 are indispensable for the bristle-inducing ability of Sens. (A) Thorax of a wild-type (Canton S) fly. (B) Ectopic expression of wild-type sens with Eq-Gal4 driver induces the formation of many extra bristles. Ectopic expression of Sens with a mutant Zn finger 1 or 4 with Eq-Gal4 driver can also induce extra bristle formation (C,F). Sens loses its ability to induce ectopic bristle formation if either Zn finger 2 or 3 is mutated (D,E). Midline bristle loss is observed in flies expressing Sens, Sens-1CC and Sens-4CC, which is due to a closure defect during thorax development when Sens retains activity. Sens-2CC and Sens-3CC do not display the dorsal closure phenotype.