Figure 10.
As in Fig. 9, active Rac on the membrane is shown for different times and cells of different shapes, but here, the Rac activation rate in the first 100s increases linearly along a short axis of the ellipsoid (from lower left corner to upper right corner), and from then on, it is rotated by 45 degrees and increases linearly in between the long and a short axis of the ellipsoids (from bottom to top). In all cases, the volume of the ellipsoid cells is fixed as V = 800μm3, the main axis is 11.5μm (spherical, (a)-(d)), 15μm ((e)-(h)) and 20μm ((i)-(l)), and the other two axes are of the same length. Comparing the different shapes, we see that the spherical cell can completely polarize into the new stimulus direction, whereas the cells with the elongated ellipsoidal shapes will rotate their internal polarization direction further than the stimulus direction, so that the polarization is more aligned with their long axis.