Fig. 9. Developing cf50^– cells move more slowly than parental Ax2 cells. Cells were starved in submerged culture for 6 hours, and then fields of cells were observed by time-lapse videomicroscopy. For each cell, the approximate center of the cell was tracked for 5 minutes, and the cell speeds were then binned in 1 µm/minute increments. The average speeds were 3.3±0.2 µm/minute for Ax2 and 2.3±0.1 µm/minute for cf50^– (means ± s.e.m. for 60 cells each, combining the observations from 20 cells in three separate experiments).