Fig. 3. Podosome filaments are compressed and store high elastic energy inside the core.

a Perspective view of a cross-section through podosome #1 displaying the mean curvature of the filaments. See also Supplementary Movie 6. The network diameter is 1.56 µm. The original tomogram has been deposited in the EMDB under accession code EMD-13666. b Gallery of a random selection of actin filaments from podosome #1. Filaments from the core (right) and outside the core (left) are shown. c, d Square of the local curvature along the filament length for the blue and purple filaments from the galleries of filaments outside (c) and inside (d) the core shown in b. e Correlation length in the ten observed podosomes. The correlation length inside the podosome core (1.68 µm on average) is smaller than outside (2.41 µm on average). Both values are smaller than those expected from thermal fluctuations of the filaments (about 10 µm³⁰), showing that energy has been spent to compress the filaments. f Density of elastic energy as a function of the radial distance from the core center for ten tomograms. Source data are provided as Source Data files.