Fig. 3.

Integrins exert vertical forces in podosome rings. a Schematic of MFM on an SLB. When an integrin receptor binds and applies forces above 4.7 pN, the probe unfolds and generates Cy3B fluorescence. Probes orient along the applied force vector, allowing determination of the tilt angle, θ, from the excitation polarization dependent Cy3B fluorescence. b Representative podosome MFM data after ~90 min cell spreading. Total tension is the maximum tension signal per pixel. Podosome zoom-ins depict the normalized Cy3B fluorescence at four different excitation polarizations. Scale bar, 5 µm. c Computed tilt angle map for the cell shown in b. Scale bar, 5 µm. d Angular histogram of average podosome tilt angle per cell, θ. Vertical forces are indistinguishable within the ~20° cone, represented by the blue region (N = 25, three experiments). Source data are provided as a Source Data file