Extended Data Fig. 7: Methods for ruffle quantification and modelling.

a) To quantify membrane ruffling, confocal z-stacks of fluorescent F-tractin were acquired at 1-minute intervals. The summed projection of these stacks created a strong signal in the tall, actin-rich ruffles, and this signal became weaker as the ruffles changed location or flattened. For each projection, a threshold was manually selected to include membrane ruffling across all frames while excluding other actin structures. The ruffle index (arbitrary unit) was then generated by integrating the thresholded area and normalizing each frame to the mean ruffle area of all the frames captured in DMEM. b) Schematic diagram depicting the interactions between model components.