Embryos expressing RhoGEF2-CRY2/CIBN::GFPpm and the membrane marker GAP43::mCherry were mounted with the ventral epithelium facing the objective. To analyze apical dynamics at each activation cycle, the photo-activation time was limited to ~ 20 s and was followed by the acquisition of a 5 µm-sized apical image stack resulting in a total time resolution of 35 s. The basal surface of the anterior (left) half of the embryo was photo-activated. (E) Diagram showing the prevalence of cells in the photo-activated region that constricted (con.) and that did not constrict (Non-con.). More than 4/5 of the cells did not constrict to half of the initial area (N = 5 embryos; n: 407 cells; Cohen's D: d = 10). In each box plot, the central mark, the bottom, and the top edge of each box indicates the median, the 25th and 75th percentile, respectively. Whiskers extent to the most extreme data point. Data information: In all panels, **** indicates p ≤ 0.0001, and n.s. indicates no statistically significant differences according to two-sample t-Test. 