Figure 4.

Lateral mobility of ALCAM molecules in the cell membrane is increased upon CytD treatment. Representative two-dimensional trajectories of ALCAM molecules attached to ALCAM^lo beads (A and B) and ALCAM^hi beads (D and E) in the absence (A and D) or presence (B and E) of CytD (2.5 μg/ml) are shown. Bars for A, B, D, and E are indicated in A. Trajectories were recorded during 120 s at a sampling rate of 100 Hz. Slow and fast diffusion coefficients were calculated from the mean square displacement versus time interval plots and are shown in C and F. Open circles represent untreated cells, and closed circles represent CytD-treated cells. Diffusion coefficients of single ALCAM molecules (ALCAM^lo beads; C) and of multiple molecules (ALCAM^hi beads; F) are shown. The average slow diffusion coefficients are summarized in Table 1.