Fig. 5.
Cic is the key component of zen repression targeted by Torso signaling. (A) Diagram illustrating the spatial relationship between Cic, Dorsal, and the Torso pathway in wild-type embryos, embryos derived from mothers with uniform Tsl expression in the follicle cells (Tub-Gal4 > UAS-tsl), and embryos from Tub-Gal4 > UAS-tsl mothers that express MAPK-insensitive forms of Cic. (B–D) Effects of uniform Torso activation on VRE-lacZ expression. (B) Control embryo expressing intact Cic. (C and D) Embryos expressing MAPK-insensitive forms of Cic produced by either a cicΔC2 transgene (4) or the cic3 allele (36), respectively. Note that both cic mutations lead to VRE-lacZ repression at the poles, since Cic is no longer down-regulated at those positions (arrowheads; compare with Fig. 1F). Photographs in B–D were taken at 200× magnification.