Fig. 4

Effect of the CMPs polarization in the signaling network and migration of the cell (A) Schematic representation of the signaling interactions. Arrows indicate positive feedback (activation) from one component to another. Tails indicate negative feedback (inactivation) of one component by another. and are the magnitudes of feedback for activating Cdc42 and Rac1 by PIP3. are the strength of the signal from receptors to GTPases or PI3K. (B–F) Two cases are shown, where the gradient of receptors that activates PI3K is always polarized toward the cathode (gray gradient) and the polarization of receptors that activate Rac1 and Cdc42 are toward the cathode (B and E) or the anode (C and F). (B and C) Evolution in time of Rac (blue), Cdc42 (red) and Rho (black), and PIPs (E and F) in the cathodal (dash) and anodal (solid) side of the cell are presented. (D) Cell migration velocity for the cases presented in (B–E) and (C–F). For the case presented in (B and C), we vary the strength of the stimulus , , and in a normal feedback loop from PIP3 to Cdc42 and Rac1 (G), when no feedback loop to Cdc42 (H) and no feedback loop to Rac1 (I). For the three cases presented in (G) in points (J–L) we vary the strength of the feedback loop from PIP3 to Cdc42 and Rac1.