Shape changes during cell migration within a substrate with a linear stiffness gradient.

<p>The substrate stiffness changes linearly in <i>x</i> direction from 1 kPa at <i>x</i> = 0 to 100 kPa at <i>x</i> = 400 <i>μ</i>m. At the beginning the cell is located at the corner of the substrate near the soft region. The results demonstrate that the cell migrates in the direction of stiffness gradient and the cell centroid finally moves around an IEP located at <i>x</i> = 351 ± 5 <i>μ</i>m. a- The cell at the middle of the substrate, b- the cell final position (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0122094#pone.0122094.s001" target="_blank">S1 Video</a>).