Dynamic coordination of F-actin remodeling with changes in traction force. (A) Top, GFP-actin images before (control) and after treatment and removal of blebbistatin. Scale bar, 10 μm. Middle, pseudocolor images of the order parameter calculated from GFP-actin images shown above, with red representing the highest order and blue representing the lowest order. Bottom, images of mApple-paxillin for the region of interest indicated by white box in GFP-actin images with traction stress vectors (red arrows) overlaid. Vector scale bar, 150 Pa. Time indicated in min:s. (B) The mean linear density of actin bundles vs. time after blebbistatin removal. Dashed line indicates a fit of the data with a single exponential, with a time scale, t_{1}, of 8 ± 3 min. Error bars indicate SE, with a sample size of 31 bundles within three cells. (C) The ratio of the peak GFP-actin intensity within bundles, I_{b}, to the GFP-actin intensity of the surrounding cytoplasm, I_{c}, as a function of time after blebbistatin removal, with each data point representing 9–12 bundles within three cells. (D) Order parameter as a function of time prior to and after blebbistatin removal. Dashed line indicates fit of data to a single exponential with a time scale of 10 ± 6 min. Data reflect mean and SE from n = 4 cells. (E) Total cellular traction force prior to and after blebbistatin removal. The relative force, calculated as a percentage, that is used in subsequent figures is shown on the right-hand axis. Dashed line indicates a fit to a double exponential with a fast time scale of t_{1} = 0.5 ± 0.5 min and a slower time of t_{2} = 10 ± 3 min. Data reflect mean and SE from n = 10 cells.

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