Fig. 1. (A) Activation of Dpp signaling using the activated receptor Tkv^Q253D produces large clones with smooth borders that minimize contact with neighboring wild-type cells. Left panels show digital camera images of the disc morphology by Hoechst 33258 DNA stain. Right panels show Flip-out/Gal4 clones in the same tissue marked with GFP. Tkv^QD clones are round (GFP), compare Tkv^QD clones (bottom right) with wild-type clones (upper right). Tkv^QD clones seem also larger than control clones. This is most obvious in areas of the tissue far from the AP boundary. For all the imaginal disc images, dorsal is upwards and anterior is leftwards. Scale bar: 100 µm. (B) Tkv^Q253D overexpression alters cell cycle phasing but not cell size. A parallel experiment, in which only GFP was expressed, was used as an external control (wt, top panels). Cells in the same tissue not expressing GFP (and therefore no transgene) were used as an internal control. Black traces correspond to the internal controls and gray filled traces correspond to the GFP-expressing experimental populations. Numbers in the top right corner of the size histograms show the ratio of the mean size of GFP⁺ cells (experimental population) versus the mean size of GFP^– cells (control population) from the forward scatter data (FSC). Expression of the activated receptor Tkv^QD causes a decrease in the G1 population and an increase in G2 population. Tkv^QD does not dramatically affect cell size. Tkv^QD has the same effects in notum and wing regions (data not shown).