Fig. 1. The knot gene is a candidate UBX-regulated target gene. (A) Knot protein (red) is expressed at the anteroposterior compartment boundary in the developing wing of Drosophila melanogaster, but is absent from the haltere (inset). Engrailed protein (green) indicates the extent of the posterior compartment, which is smaller in the haltere than in the wing. (B) The distribution of Knot protein in D. pseudoobscura is identical to that in D. melanogaster. (C) In mitotic clones that overexpress UBX protein (blue), Knot is cell-autonomously repressed. (C) Courtesy of Ron Galant.