Figure 1. Rac1 overexpression in ISCs drives ROS production in the adult Drosophila midgut. (A) Tracing of an adult Drosophila gastrointestinal tract. The dotted box highlights the region of the posterior midgut, which was used for our studies. (B–C') Posterior midguts of animals incubated at 29 °C during 2 d to induce the expression of gfp only (B and B') or gfp and Rac1^wt (C and C') under the control of the intestinal stem cell (ISC)/enteroblast (EB) diver escargot-gal4 (esg^ts > gfp and esg^ts > Rac1^wt, respectively). Midguts were dissected and stained with DHE (red) to detect ROS production and anti-GFP (green) to label esg^+ve cells. Scale bars: 20 μm.