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. Author manuscript; available in PMC: 2016 Sep 8.
Published in final edited form as: Nat Cell Biol. 2015 Dec 21;18(2):191–201. doi: 10.1038/ncb3292

Figure 4.

Figure 4

Basal Cdc42 activity fluctuations in morphologically unpolarized cells predict the future direction of cell polarization. (a) Examples of morphologically unpolarized cells with asymmetric Cdc42 activity prior to stimulation (left panels). Pink arrows indicate the site of pre-existing Cdc42 activity at cell periphery. Cdc42 activity is indicated by the color scale. Scale bar is 10μm. (b) Schematic representation for analyzing the angular difference between direction of movement and direction of the maximal peripheral GTPase activity prior to stimulation. Shown are the contour of the edge of a cell before stimulation, colored according to the FRET ratio, overlaid with the contour (in gray) of the same cell after polarization and initial movement. Scale bar is 10μm. (c) Rose plots showing distributions of the angle between the maximal local GTPase activity before stimulation and the subsequent migration direction. Red color indicates angles between -30 and 30 degrees. P-values were calculated using the sign test applied to the cosine of the angles. * indicates p-value is less than 0.0001. n=68 (Rac), n=69 (Cdc42), n=63 (Ras), and n= 65 (RhoA) cells.