Fig. 4. The actin core generates elastic forces in the nanonewton range.

a Comparison of the elastic force generated by the core through the compression of the actin network (“Elastic”; black) with the estimated polymerization force generated at the core membrane (“Polymerization”) with the upper (“(10 pN)”; purple) and lower (“(1 pN)”, cyan) limits of the polymerization force. The blue dashed line corresponds to the mean force derived from PFM measurements on 30-nm thick Formvar films (“PFM (Formvar)”)¹⁷. b Same comparison plot as in a for the estimated pressure assuming a perfect circular shape for the podosome core (Methods). c Summary scheme showing the podosome organization revealed by cryo-ET, the elastic force resulting from core compression and the radial surface tension counterbalancing it. The tension of the 2D meshwork of radial filaments that is required to balance the core compression force is deduced from the mean radius of the core, r_core, and the mean angle of the radial filaments, θ_radial, with respect to the membrane plane. Source data are provided as Source Data files.