Models. (A) Model of regulation of mobile E-cad distribution by dynamic MTs. EB1 at MT plus ends sequesters RhoGEF2, suppressing Rok localization at DV borders. This releases inhibition of mobile E-cad–Baz, elevating it at DV borders. (B) Model of formation of a five-cell rosette (right, arrowhead) from four-cell contact (left) through either “unzipping” of the DV border (red, arrow) and reattachment with the AP border (red/black) or membrane internalization (red, arrows). (C) Model of cell crossing of the segment border through rosette resolution (blue asterisks). The collapsing junctions are in red, the newly formed junctions are in blue, and those changing from AP to DV are in yellow.