The actin-based nanomachine at the leading edge of migrating cells

Biophys J. 1999 Sep;77(3):1721-32. doi: 10.1016/S0006-3495(99)77018-9.


Two fundamental parameters of the highly dynamic, ultrathin lamellipodia of migrating fibroblasts have been determined-its thickness in living cells (176 +/- 14 nm), by standing-wave fluorescence microscopy, and its F-actin density (1580 +/- 613 microm of F-actin/microm(3)), via image-based photometry. In combination with data from previous studies, we have computed the density of growing actin filament ends at the lamellipodium margin (241 +/- 100/microm) and the maximum force (1.86 +/- 0.83 nN/microm) and pressure (10.5 +/- 4.8 kPa) obtainable via actin assembly. We have used cell deformability measurements (. J. Cell Sci. 44:187-200;. Proc. Natl. Acad. Sci. USA. 79:5327-5331) and an estimate of the force required to stall the polymerization of a single filament (. Proc. Natl. Acad. Sci. USA. 78:5613-5617;. Biophys. J. 65:316-324) to argue that actin assembly alone could drive lamellipodial extension directly.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3 Cells
  • Actins / physiology*
  • Animals
  • Calibration
  • Cell Movement*
  • Cell Size
  • Cytoplasm / physiology
  • Cytoplasm / ultrastructure
  • Mice
  • Microscopy, Electron
  • Microscopy, Fluorescence / methods
  • Models, Biological


  • Actins