FIGURE 1.

Schematic representation of the experiment. The cell is first allowed to spread for at least 30 min. Then a microfabricated pillar is contacted from above and kept there for ∼15 min to ensure stable adhesion between pillar and cell. Culture conditions are chosen such that the actin cytoskeleton (red) is in a homogeneous state (no stress fibers). When the pillar is shifted to the side, the cytoskeleton is strained and the FAs adapt their size to the new loading situation. Typically, this takes 15 min. In the stationary state, the sizes of the focal adhesions (green) are expected to be proportional to the forces transmitted through the cytoskeleton.