a–c, Time-lapse imaging of SOP cells in control and RacGAP1-depleted backgrounds was carried out to analyse the relative timing of polar relaxation and anaphase elongation. We analysed cells from five control animals and four RacGAP1 RNAi animals. Representative images are shown in a (scale bars, 5 µm). White arrowheads indicate actin clearance at the poles. Lifeact–GFP was used to label F-actin. For control and RacGAP1 RNAi cells that formed a furrow (n = 19 and n = 16, respectively), the period between anaphase onset and furrow initiation or furrow completion is plotted in b (black lines denote the median). Cell length is plotted in c for the control group (18 cells) and for RacGAP1 RNAi cells that were delayed in furrow formation (15 cells) or that failed to form a furrow (5 cells). d, Relative levels of polar actin were compared across movies of 12 control RNAi cells from four animals (same as seen in Fig. 2e) and from 12 RacGAP1 RNAi cells from three animals. Ana, anaphase; Met, metaphase. e, Graph shows the ratio of levels of cortical actin at poles versus the equator at mid anaphase for 20 control cells from five animals, and for 13 RacGAP1 RNAi cells from three animals. Data are shown as mean and s.d. in c and d, and as box-and-whisker plots with 10–90 percentiles in e. A two-tailed unpaired t-test was used to calculate statistical significance; P > 0.05 was deemed not significant (n.s.).