FIGURE 2.

Model of the cell envelope as a composite soft shell composed of the lipid-protein bilayer and the associated actin cortex (assumed to form a partially cross-linked network of the semiflexible actin filaments). The force probe is coupled to the actin cortex through integrins. The apical shell of the cell may be coupled to the lower (basal) cell envelope adhering to the substrate (similar to Bausch et al., 1998). The coupling (represented here by springs) can be mediated by the microtubuli and the intermediate filaments of the cytoskeleton.