Fig. 4. Roe represses N signaling targets during leg disc patterning. Panels show leg discs, with anterior leftwards and dorsal upwards. Wg (blue, negative control) is expressed in a ventral wedge at the A/P boundary in a N-independent manner. (A,A') Bib (red, monochrome in A') is expressed in concentric rings in leg discs, corresponding to the presumptive leg segment joints defined by N signaling. (B,B') dpp^GAL4-driven N^ECD ectopic expression (marked by GFP, green) causes a cell-autonomous expansion of Bib expression inside the dpp^GAL4 domain. (C,C') Ectopic expression of Roe under the control of dpp^GAL4 (green) causes cell-autonomous repression (arrowheads) of Bib (red, monochrome in C'). (D,D') The E(spl)mβ1.5-Z reporter line (mβ-lacZ red and monochrome) is regulated by N signaling and expressed in concentric rings corresponding to presumptive cells of the leg joints. (E,E') dpp^GAL4-driven ectopic expression of Roe (green) causes cell-autonomous repression (arrowheads) of mβ-lacZ (red, monochrome in E').