Abstract
Intracellular and extracellular mechanical forces affect the dynamics of actin cytoskeletons, however, the underlying biophysical mechanisms how forces are transduced into changes in the actin dynamics remain largely unknown. We find that activity of the actin severing protein ADF/cofilin negatively depends on tension in the actin filament through tension-dependent binding/unbinding of cofilin to/from the actin filament, thereby relaxed actin filaments are severed whereas tensed ones are not. Here we review the latest knowledge on this phenomenon and discuss its biological impact.