Rigidity sensing explained by active matter theory
  The magnitude of traction forces exerted by living animal cells on their environment is a monotonically increasing and approximately sigmoidal function of the stiffness of the external medium. This observation is rationalized using active matter theory: adaptation to substrate rigidity results from an interplay between passive elasticity and active contractility. 
P. Marcq, N. Yoshinaga and J. Prost
q-bio.QM