Fig. 4. Dynein exhibits unidirectional movement in both retrograde and anterograde directions. Time-lapse images of dynein-GFP in living cells. (a) Retrograde movement (see also Movie 1 at jcs.biologists.org ). (b) Anterograde movement (see also Movie 2 at jcs.biologists.org ). The arrowhead indicates the position of a single dynein-associated structure in each frame. The last panels of (a) and (b) show the track of the moving vesicle by superimposing dots marking the position of the indicated dynein-containing structure from each frame. It is worth noting that each of the video sequences shows a variety of movement types. A single example in each video has been highlighted for simplicity. The elapsed time is shown as `seconds.milliseconds'. Scale bar, 5 µm.