A-E. Lateral views of stage 11 Drosophila embryos immunostained for β-gal (green), Ato (red), and/or Sens (purple) as indicated. Close-ups of thoracic and abdominal segments (A1 labeled) are shown at right. PrdG4 is expressed in every other segment including the first abdominal segment (A1) and the T2 thoracic segment. The PrdG4-negative segments that do not drive UAS gene expression are noted by arrows in A-D. PrdG4;UAS-Ato embryos reveal that ectopic Ato induces RhoBAD-lacZ (A), RhoAAA-lacZ (B), RhoAAAHoxM-lacZ (C), and RhoDD-lacZ (D) activity. PrdG4;UAS-Sens embryo shows that ectopic Sens does not significantly alter RhoBAD activity (E). Note, however, that while many more cells express Sens, Sens levels in the C1 lineage (arrows) are not dramatically different between the PrdG4-on versus PrdG4-off segments.