Figure 2.

Cells can achieve moderate net cell displacements during a single bleb cycle in viscoelastic environments without adhesion-based forces, thanks to the differential shear rates associated with bleb growth and retraction phases. (A,B) Snapshots of the magnitude of the fluid velocity and velocity vectors (A), and hydrostatic pressure (B) acquired at two time-points during early bleb expansion and early retraction. ${\text{K}}_{\text{τ}}=100$ for panels (A) and (B). (C−E) Time-evolution of the cell centroid for three different values of the cortex turnover parameter ${\text{K}}_{\text{τ}}$ (C), for three different values of the number of myosin molecules inside the cell ${\text{N}}_{\text{myo}}$ (D) and three different values of the cortical stiffness per unit of actin parameter ${\text{κ}}_{\text{c}}$ (E). Greater cell displacements are achieved for slower cortical turnover kinetics, and a more contractile and softer cortex. In all panels, membrane-cortex linkers are broken by hand locally in a small region at time t = 0, mimicking a local downregulation of membrane-cortex linkers due to a chemical signal or force. Polymeric model parameter values: ${\text{η}}_{\text{p}}^{\text{in}}=1\text{pN}\cdot \text{s}\cdot {\text{μm}}^{-1},{\text{λ}}_{\text{p}}^{\text{in}}=100\text{s,}{\text{η}}_{\text{p}}^{\text{out}}=1\text{pN}\cdot \text{s}\cdot {\text{μm}}^{-1}\text{,}{\text{λ}}_{\text{p}}^{\text{out}}=10\text{s}$.