FIGURE 4.
A typical area growth curve plotted as log-log plot (stimulation with a gradient of fMLF—same cell as Fig. 3 B). The open circles represent the data. The slow growth regime is fitted to a line (solid) with slope of 0.2. The fast growth regime is fitted to a single line (solid) of slope 0.9. Also indicated are three broken lines in the fast growth regime running next to the data points which represent piecewise fits (laterally shifted in position for clarity) with slopes 0.6, 1.0, and 0.7. The insets show trinary images of the cell corresponding to the indicated times. Note that the first change in slope marks the transition from slow to fast spreading and corresponds to the appearance of the first point of persistent close contact. The point marked A corresponds to the beginning of retraction of the uropod, and the point B marks the point at which the uropod retraction rate overtakes the lamellipod-spreading rate, resulting in a drop of the total area. (See supporting material for a similar plot along with the time-lapse images for the uniform stimulation case.)