Fig. 3. VP16En activates genes that are normally repressed by En. Embryos placed side by side are of the same genotype except that embryos on the right-hand side express VP16En under the control of paired-Gal4. (A,B) Expression of ci in the abdominal region of wild-type (A) and paired-Gal4 UAS-VP16En (B) embryos. In the wild-type (A), ci is repressed by En in every segment. paired-Gal4-driven VP16En leads to ectopic activation of ci expression thus blotting out repression in alternate segments (B). (C,D) Expression of wg in the abdominal region of wild-type (C) and paired-Gal4 UAS-VP16En (D) embryos. Expression of wg is broadened in response to VP16En expression in alternate segments (D). (E) Expression of wg in a ci^CE embryo. No expression is detectable in the segmented ectoderm. This is expected because Hh signaling (hence Ci) is required for continued wg expression (Tabata et al., 1992). (F) Expression of wg in a ci^CE embryo that expresses VP16En under the control of paired-Gal4. Ectopic expression of wg is induced even though Ci is absent, consistent with the possibility that VP16En could activate wg expression directly.