Fig. 3. Groucho is phosphorylated by the Torso pathway. Wild-type (A) or mutant (B-F) stage 5 embryos, stained with pGro (A,B,C,E) or Gro (D,F) antibodies. The genetic inactivation of the Torso pathway, in tsl⁶⁹¹ mutant embryos, leads to loss of pGro from the termini (B; compare with A). Reciprocally, pGro staining expands to more central regions in tor^Y9 mutants, in which the Torso receptor is overactive, and a higher than normal uniform staining is observed throughout the embryo (C; compare with A). (D) A tor^Y9 mutant embryo stained with the Gro antibody, showing a larger posterior domain devoid of staining (compare with Fig. 2B). The central pGro stripes are not dramatically affected in either tsl⁶⁹¹ or tor^Y9 mutants. (E,F) A stage 5 DSor mutant embryo (GLC), stained for pGro (E; red) and Gro (F; green). pGro staining is absent from the termini (E; compare with A), and is replaced by Gro staining, which is not detected normally in this region (compare with Fig. 2B). There are seven pGro stripes in the DSor mutant (E).