Fig. 3. Long-range movements of WPb in HUVECs. (A) Long-range directed motions visualized by thresholding and accumulating frames from a sequence of 120 images. Bar, 10 µm. (B) Example of long-range directed motion. The three-dimensional trajectory is shown in the left-hand panels. Note the difference in scale between the z-axis and the x-y axes. The initial point (t=0) is indicated by an asterisk. The right-hand panel shows plots of vertical position z (solid line, left axis in µm) and velocity (dotted line, right axis in µm/second) as a function of time, with a rolling average of three frames. The WPb slows down as it approaches the plasma membrane (arrows) and accelerates as it moves away from the membrane (arrowheads). (C) WPb rotation. Plot of the angle of a rotating WPb as a function of time (anticlockwise rotation, frequency _rot=0.40 per second). Top panels show the corresponding TIRF images (Bar, 1 µm). (D) WPb oscillations. Plot of the x-y velocity of an oscillating WPb as a function of time (oscillation frequency _osc=0.14 per second).