Fig. 4.

Liquid-like motor properties of cells. (A) The rheological model leads to a Hill-type Eq. 3, which matches quantitatively the experimental data both during loading (blue curve at $L_0-L=1\mu \text{m}$, force velocity in 1D model; boxes, experiments) and at equilibrium (surface intercept with $v=0$, 1D model; red curve, 3D model; circles, experiments). Dotted lines correspond to the force–distance relationship imposed by a given microplate stiffness k. Same parameters are used as in Fig. 2. (B) Power use in a microplate experiment as a function of the external load F: only a small part of the load-independent myosin power is being transmitted to the cell environment as mechanical power; the rest is dissipated internally or compensates the antagonistic role of polymerization. Boxes are the experimental results to be compared with the dashed line, which is mechanical power at $L_0-L=1\mu \text{m}$. Solid lines correspond to $L=L_0$. Same parameters are used as in Fig. 2.