Fig. 1: Cell migration speed correlates with intracellular diffusion.
a–d Cell loaded with QDs: a migrating keratocyte (a), QDs loaded in the cell (b), overlay of QD movies in the reference of cell frame (c) and QD trajectories (d). The upper and lower regions in each figure correspond to the lamellipodium and the cell body, respectively. Scale bar, 10 μm. e Typical QD trajectories in the lamellipodium and the cell body, showing distinct dynamic diffusion behaviors. f MSD plots of QDs in two sub-regions of migrating cells (n = 10) and in fixed cells (n = 7). Slopes of MSD curves are 0.98 and 0.74 for lamellipodium (total trajectories, 1863) and cell body (total trajectories, 686), respectively. g Cell speed and QD diffusion rate D as a function of time for a single migrating cell. h–j, Cell displacements (h), QD trajectories for 50 frames (I), and MSD plots (j) at three time points (I–III, indicated in (g)). Data are presented as mean ± SE. k Distributions of D at the three-time points with averages at 0.72, 0.99, and 0.64 μm2/s, respectively. The trajectory numbers are 115, 275, and 148 for I–III, respectively. l The average migrating speed of each cell is plotted against the average D in its lamellipodium for a total of 66 cells. Source data are provided as a Source Data file.
