FIGURE 6:

Polarity establishment is robust to variations of the initial distributions of the cytoskeletal meshworks and of the boundary conditions. Initial (top row) and evolved (bottom row) distributions of the actin networks and polarity molecules. In all initial conditions, the Rac and Rho molecular distributions are random. (a) Periodic boundary conditions are used to represent the circular cell edge. Initially, there is one peak of the bundled network density but three peaks of the branched network density, two of which colocalized with the bundled network. (b–d) The model on the 1D segment with no-flux boundary conditions representing the anterior–posterior cross-section of an elongated cell. (b) Initially, the ends of the cell are contractile, while the middle is protrusive. (c) Initially, the cell ends are protrusive, while the middle is contractile. (d) Initially, both protrusive and contractile networks are concentrated at the cell center. In all cases, the same polarized state with segregated protrusive and contractile networks evolve. Notably, for the segment-like cell, the networks segregate to the opposite ends of the cell, making the cell robustly motile.