Figure 2. Analysis of actin motility.

A, superposition of 90 sequential video frames from one representative recorded fluorescence microscopy field. White traces indicate the paths of RhPh-labelled actin filaments over 3 s. Actin filaments in the last frame are indicated in black. Scale bar 10 μm. B, rectangular area from A magnified to illustrate measurement of the distance travelled by the trailing ends of three actin filaments. The trailing end of each actin filament is marked with a dot in the first frame and with an arrowhead in the 90th frame. Each path contour begins at the dot and proceeds to the arrowhead. Hence, the arrowheads also represent the direction of filament sliding.