ABSTRACT
Observation of epidermal cells or cell fragments on flat adhesive substrates has revealed two distinct morphological and functional states: a nonmigrating symmetric “unpolarized state” and a migrating asymmetric “polarized state.” They are characterized by different spatial distributions and dynamics of important molecular components as F-actin and myosin-II within the cytoplasm, and integrin receptors at the plasma membrane contacting the substratum, thereby inducing so-called focal adhesion complexes. So far, mathematical models have reduced this phenomenon to gradients in regulatory control and signaling molecules or to different mechanics of the polymerizing and contracting actin filament system in different regions of the cell edge.
