Fig. 5. Alternate movements of beads did not occur in MHC-null cells. Representative movement of the beads around a migrating MHC-null cell (a-d). The gray and black lines represent a superimposed image of two cell contours at 0 seconds and 120 seconds in a, at 120 seconds and 240 seconds in b, at 240 seconds and 360 seconds in c, at 360 seconds and 480 seconds in d, respectively. Large closed arrows represent the direction of cell migration. The gray and black dots represent positions of the beads at 0 seconds and 120 seconds in a, at 120 seconds and 240 seconds in b, at 240 seconds and 360 seconds in c, at 360 seconds and 480 seconds in d, respectively. The bead movement did not reverse. Insets in c and d, schematic images of the direction of movement of beads surrounding the cell. The bead movements showed only the pattern 1 observed in wild-type cells. (e) A representative time course of the gained area of a migrating MHC-null cell. Note that MHC-null cells also repeated two phases, extension and retraction phases. The average time of a single cycle was 151.7±38.0 seconds (n=15). (f) The displacement of the posterior and the anterior edges of the cell was plotted over time. Note that the position of the posterior edge moved roughly at a constant rate when compared with the case of wild-type cells (see Fig. 4b), whereas the rate of the displacement of the anterior edge had obvious peaks (arrows in f). The cell shown in e and f was different from the cell in a-d. The stiffness of silicone substrate was 5.97 nN/µm. Bar, 5 µm.