(A-C) Embryos co-expressing CIBN-PatJ::GFPpm, RhoGEF2-CRY2::mCherry and the membrane marker GAP43::mCherry were photo-activated at the cell base after cells had already apically constricted. (A) Prior to photo-activation, cells were apically constricted and elongated. (B) In the non-activated region, within 6 min cells expanded their base and shorten. (C) In the photo-activated region, cell shortening was inhibited. (D-F) Cellular features extracted from the reconstructed cell shapes displayed in boxplots (pre A: pre activation (npre A = 107), initial time point; NR: non-activated region (nNR = 10); AR: activated region (nAR = 37)). The central mark, bottom and top edges of each box indicate the median, 25th and 75th percentile, respectively. Whiskers extent to the most extreme data point and the '+' symbol indicates an outlier. Notches indicate comparison intervals. (D) The mean cell length at the initial time point was 45 µm (blue). 6 min after, the non-activated cells (green) shrank to about half of the size (26 µm), whereas photo-activated cells (red) only shrank to 39 µm. ANOVA result: F(2,151)=110.2, p=3e-30; Cohen's D: d > 1.5 for all comparisons. (E) The basal area in the pre-activation control of 30 µm enlarged to 60 µm in the non-photo-activated cells, but remained at 30 µm in the activated region. ANOVA result: F(2,151)=52.02, p=6.5e-18; Cohen's D: dpreA:NR, dAR:NR > 2, dpreA:AR < 0.5. Please note the logarithmic y-axis. (F) The cell volume did not change between the different conditions. There were no statistically significant differences between group means as determined by one-way ANOVA (F(2,151)=2.227, p=0.11). In all panels, **** indicates p ≤ 0.0001, and n.s. indicates no statistically significant differences according to two-sample t-Test. 