Fig. 5. Pros expression in LG depends on Dl-N signaling through neuron-glial interactions. All panels (except C and H) show three segments of a stage 15-16 VNC with the axon tracts shown in green (anti-HRP) and Pros in magenta. (A) Misexpression of UAS-fng with htl-Gal4 leads to ectopic expression of Pros in posterior LG, labeled 7 and 8. (B,C) Ectopic Pros is also observed upon misexpression of either Dl (B) or Ser (not shown) in postmitotic neurons using elav^C155-Gal4. (C) Co-labeling for Pros (green) and the LG marker Distal-less (magenta) shows that the ectopic Prospositive cells are indeed posterior LG. (D) By contrast, Pros is inhibited upon misexpression of Dl in LG with htl-Gal4. (E) Pros expression in fng mutants is further reduced in embryos also heterozygous for Dl^rev10 (compare with Fig. 2D). (F) Pros expression is unaffected in Ser^rev2-11/Ser^Rx82 mutants. (G) Fewer cells express Pros in embryos in which misexpression of UAS-Tom is driven by scrt^11-6-Gal4 in neuronal lineages. (H) Three segments of a stage 16-17 embryo with scrt^11-6-Gal4 driving UAS-Tom. Anti-Eve immunochemistry revealed no transformations of cell fate of RP2 (arrows) or other Eve-positive neurons. (I) Pros expression is unaffected by Tom misexpression in LG.