Fig. 2: Fast and slow migrating cells show distinct intracellular diffusion maps and lamellipodium structures.

a–c QD diffusion maps (a), QD trajectories (b), and CMFDA fluorescence images (c) for migrating cells with fast and slow speeds and for cells treated with 10 nM latrunculin A (LatA) or 50 μM blebbistatin (Bleb). The color range from blue to red corresponds to Dp (local diffusion rate) from 0 to 0.8 μm2/s. The cells are to move upwards, with their outlines and cell body regions labeled by yellow lines. d STED imaging of actin filaments labeled by SiR-actin in fixed cells at the four indicated cell conditions. e Average D and migration speeds for cells at four conditions (fast, n = 16; slow, n = 16; LatA, n = 15; Bleb, n = 14). Data are shown as mean ± SD. f, g Normalized intensity profiles of QD movie projection (f) and CMFDA (g) along a line across the lamellipodium, from the cell body to its leading edge (dotted line). h FRAP of the CMFDA intensity in the front lamellipodium at four conditions, with the fitted recovery times: 0.73 ± 0.18 s (fast, n = 35), 1.09 ± 0.37 s (slow, n = 40), 1.06 ± 0.30 s (LatA, n = 19) and 1.04 ± 0 .25 s (Bleb, n = 20). The solid lines and the shaded regions represent mean ± SE. Inset schematic for the FRAP region in the front lamellipodium. Scale bar, 10 μm. Source data are provided as a Source Data file.