Figure 3.

Actin and myosin dynamics in retraction fibers and on apical surface of the cell body. Movement of actin toward (A) and of myosin II toward (B) and away (C) from the cell body in retraction fibers. (D) Retraction fibers retain actin filaments after cytochalasin D treatment: phase-contrast image on the left and phalloidin labeling on the right. (E–H) Dynamics of myosin II in retraction fibers after treatment with cytochalasin D. (E) Bidirectional movement of myosin II in a single fiber. (F) Lack of motion of myosin features in fibers of the cells treated with blebbistatin and cytochalasin D. Phase-contrast (G) and tetramethylrhodamine–myosin fluorescence microscopy (H) sequences of zipping of two branched fibers. (I) Forward motion of actin with respect to the cell on the apical surface of the cell body (7.5 μm from substrate). (J) Actin velocity in the cell body varies with the distance from the substratum. SD and mean cell speed (horizontal line) are indicated. Leading edge of the cell is up; all images are aligned with respect to the cell. Bars, 1 μm. Time is indicated in seconds.