The M region regulates the levels of AJ components. (A) Stills of live α-Cat-RNAi α-CatX embryos at stage 8 (rapid phase of germband extension, 3:10–3:40 h after egg laying) expressing Ecad::GFP and Vinc::mCherry. (B) Stills of live α-Cat-RNAi α-CatX embryos at stage 8 expressing Jub::GFP. Scale bar for A and B, 10 μm. (C) FIs of junctional signal of Vinc::mCherry, Ecad::GFP, and Jub::GFP in α-Cat-RNAi α-CatX embryos at stage 8. The ratio of cortical Vinc to Ecad per cell is given as Vinc/Ecad. n = a pooled number of cells (c) from a number of embryos (e); Ecad, Vinc, and Vinc/Ecad are measured from the same cells. Bold line, median; dotted lines, interquartile ranges. Significance calculated by Kruskal–Wallis test with Dunn’s multiple comparison test for Ecad, Vinc, and Vinc/Ecad and ordinary one-way ANOVA with Tukey’s multiple comparison test for Jub (**** = P < 0.0001, * = P < 0.05). (D) Balloon plot summarizing changes in mean junctional fluorescent signals. (E) Schematic illustration of the functional relationship between M1, M2, and M3 in respect to the recruitment of Vinc to the AJ.