Figure 4.

Fv relationships when lamellipodia lifted up the bead along the z direction. (a) The F_z component of the force when the lamellipodium of Fig. 2 pushed the bead vertically. The dotted box indicates the section of force measurement used to compute the Fv relationship after Gaussian filtering at 0.2 (green), 1 (pink), and 10 Hz (black). (b and c) Fv relationships obtained after smoothing at 0.2 Hz (b, green trace) and 1 Hz (b, pink trace) and at 10 Hz (c). (d) Superimposed Fv relationships from 29 experiments normalized to F_max from data filtered at 0.2 Hz. The black line represents −3σ_v at the 0.2-Hz bandwidth (where σ_v was calculated from bead fluctuations measured away from the lamellipodia). (e) <Fv>_x relationships normalized to F_max. Data were filtered up to a bandwidth of X Hz. <Fv>_0.2 (green), <Fv>₁ (pink), and <Fv>₁₀ (black).