Fig. 4. Abberant expression of homeotic genes in Pc mutant clones. Confocal images of wild-type control and Pc mutant MARCM clones labeled with membrane-tethered GFP (CD8::GFP, white) and immunostained as indicated. Shown are late third-instar ventral ganglia (A-F, outlined with dots) or close-up views on the central brain (G-I), anterior at the top. (A-C) Large wild-type clones are visible in the thorax which contains most of the proliferative neural precursors (labeled for Mira or Grh, blue). Hox genes of the Bithorax complex are expressed in restricted domains along the anteroposterior axis. (D-F). Small Pc clones show ectopic anterior expression of the homeotic genes (white and magenta). Ectopic expression of UBX (F) is not as widespread as Abd-B (D) or Abd-A (E). (G-I) Variability in Hox gene derepression is also evident on the close-up views of isolated small clones in the brain. Scale bars: A-F, 25 µm; G-I, 20 µm.