Movie 6.

Myosin II is preferentially recruited during the initiation of the AP boundary. Time-lapse movies showing the photoconversion of Sqh::Dendra2 at the three developmental phases. A merge overlaying red channel pixel intensities of photoconverted Sqh::Dendra2 (color) and the green channel pixel intensities of non-photoconverted Sqh::Dendra2 (grey) is shown. Blue and orange arrowheads point towards the AP cell junctions and the junctions facing cells of the same compartment, respectively. Scale bars are 5 μm.