Traction stress in focal adhesions correlates biphasically with actin retrograde flow speed

J Cell Biol. 2008 Dec 15;183(6):999-1005. doi: 10.1083/jcb.200810060.


How focal adhesions (FAs) convert retrograde filamentous actin (F-actin) flow into traction stress on the extracellular matrix to drive cell migration is unknown. Using combined traction force and fluorescent speckle microscopy, we observed a robust biphasic relationship between F-actin speed and traction force. F-actin speed is inversely related to traction stress near the cell edge where FAs are formed and F-actin motion is rapid. In contrast, larger FAs where the F-actin speed is low are marked by a direct relationship between F-actin speed and traction stress. We found that the biphasic switch is determined by a threshold F-actin speed of 8-10 nm/s, independent of changes in FA protein density, age, stress magnitude, assembly/disassembly status, or subcellular position induced by pleiotropic perturbations to Rho family guanosine triphosphatase signaling and myosin II activity. Thus, F-actin speed is a fundamental regulator of traction force at FAs during cell migration.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Actins / metabolism*
  • Cell Movement*
  • Focal Adhesions / metabolism*
  • Myosin Type II / metabolism
  • Pseudopodia / metabolism
  • Rheology
  • Signal Transduction
  • Stress, Physiological*
  • rho GTP-Binding Proteins / metabolism


  • Actins
  • Myosin Type II
  • rho GTP-Binding Proteins