Movie S5.

Tracking the position, motion, and orientation of AF488-phalloidin particles attached to F-actin in a cell withdrawing its leading edge. (Upper Left) Average image of four quadrants showing actin network sparsely decorated by AF488-phalloidin. (Upper Right) Tracks trailing behind the detected fluorescent particles are shown by green lines. (Lower Left) Flow direction and flow speed along detected tracks are shown by directions of green arrows and their lengths, respectively. Arrows are placed with their base at the position of the particles. (Lower Right) Measured polarization orientation and polarization factor are shown by the orientations of the magenta lines and their lengths, respectively. The lines are placed with their center at the position of the particles. Time from the start of the video is shown in the upper left corner in minutes:seconds format. (Scale bars: white, 1 µm; green, 25 nm/s; magenta, p=1.)