Fig. 8. Influence of Cdc42 on localisation of the Mbt protein. (A-I) Two ommatidial clusters of an eye imaginal disc derived from an animal of the genotype Cdc42⁴, FRT 19A/tubP-Gal80, hs-Flp, FRT19A; GMR-Gal4/UAS: mCD8-GFP are shown. The eye disc was stained with the anti-Mbt serum (red) and the anti-mCD8 antibody (green). Heat-shock induced Flippase (Flp) activity produces recombination between the FRT19A bearing chromosomes resulting in daughter cells, which are homozygous for the cdc42⁴ mutation and at the same time lack the Gal4 suppressor Gal80. This allows expression of the GMR-Gal4-driven mCD8-GFP reporter gene in homozygous cdc42⁴ cells. Apical-to-basal projection views of an eye disc containing a single cdc42⁴ mutant photoreceptor cell are shown in A (anti-Mbt), B (anti-mCD8) and C (merge); D-F focus on the most apical domain; G-I are apicobasal cross-sections. The cdc42⁴ mutant cell is devoid of detectable levels of Mbt protein (arrowheads), while the other photoreceptor cells express high levels of apical localised Mbt protein. The arrow indicates to the axonal projection. (K-N) Localisation of Mbt and Arm in third instar eye imaginal discs upon expression of Cdc42^T17N (K,L) and Cdc42^G12V (M,N). Scale bars: 5 µm in I; 10 µm in N.