Fig. 5. Expression of the Wg target gene ac is altered in clones lacking HS polymerase activity. In wild type (A), Ac is expressed in the anterior compartment in cells on either side of the Wg expression domain. Ac expression is reduced or lost in ttv (B), sotv (C) or both ttv, sotv (D) mutant clones (see arrows). Occasionally, ectopic Ac is observed in the vicinity of the mutant clone (B, arrowhead), which correlates with the location of ectopic margin bristles in wings from mosaic adults (see Fig. 3D-F).