a, PIV analysis performed on a LifeAct-GFP-expressing cell to highlight the direction and magnitude of actin flow. The region of the flowfield without vectors represents the soma of the haemocyte, which has no observable actin flow, and this information was removed for all subsequent quantification. Scale bar, 10 µm. b, Divergence calculated from the actin flowfield to highlight sinks within the network. In this image, only negatively divergent regions are highlighted. a.u., arbitrary units. c, Streamlines calculated from the actin flowfield in which streamlines were seeded along the boundary of the cell. d, The confluence of streamlines quantified by calculating the number of streamlines ending in any location within the cell. In this image, the size of the spot is normalized to the number of streamline endpoints. e, The actin flow divergence calculated at the primary sink and compared with the divergence values averaged across the entire cell. ***P < 0.0001, Mann–Whitney two-tailed test. Boxplot shows medians, 25th and 75th percentiles as box limits, 10th and 90th as whiskers (n = 443, 9 biologically independent samples). f, A correlation map in which the direction of cell motion was correlated to the direction of every actin flow vector within the cell. Note that a positive correlation highlights anterograde flow while a negative correlation denotes retrograde flow. The circle with a broken outline indicates the location of the primary sink in this frame of the video. g, Quantification of the gradient of the correlation map in f reveals sharp transition regions within the flowfield. The circle with the broken outline indicates the location of the primary streamline sink in this frame of the time-lapse video. h, Quantification of the gradient of the retrograde–anterograde flow correlation, as highlighted in f and g, at the primary streamline sinks compared to the gradient values averaged across the entire cell. ***P < 0.0001, Mann–Whitney two-tailed test. Boxplot representation as in e (n = 443, 9 biologically independent samples).