Movie 2.

Time-lapse live imaging of mosaically expressing ventral ectoderm from stage 13 embryos using Andor BC43 confocal microscope (20 × objective lens). Four-cell embryos were coinjected with 50–100 pg of RNAs encoding ΔN-Mrtf (250 pg), mNeonGreen-Sf9 (green, 50 pg) and Scarlet-UtrCH (magenta, 50 pg). Top view shows apical domain reduction in several cells as compared to apical domain size of their neighbors. Length of the movie 60 min with 3 min intervals.