Fig. 7. Blockage of N delivery to the late-endosome inhibits the activation of Dx-mediated N signaling. (A-C) Overexpression of Rab5^S43N, a dominant-negative form of Rab5, along the AP boundary of the third instar wing disc did not show a detectable effect on endogenous vgBE activation (green in A and C). Endogenous expression of Dx was also detected (purple in B and C). (D-F) Co-expression of Dx (purple in E and F) and Rab5^S43N along the AP boundary resulted in inhibition of the ectopic activation of vgBE (green in D and F) associated with Dx overexpression. (G-J) In the apical region of the epithelial cells overexpressing Dx (blue in I and J) with Rab5^S43N, N (green in G and J) accumulated in unusually large Hk-positive vesicles (purple in H and J), where Dx was co-localized with N (shown by white arrowheads). (K-N) In the basal region of the cells overexpressing Dx (blue in M and N) with Rab5^S43N, the accumulation of N (green in K and N) in the late-endosomes was not detected (compare to Fig. 4B). UAS-dx and UAS-Rab5^S43N were driven by dpp-GAL4 (A-F) or ptc-GAL4 (G-N).