English: Dynamical simulations of cell shape for different adhesion drag coefficents recapitulate experimentally observed differences in cell shape. Cell shape and actin network flow were simulated using an iteration procedure: myosin densities and centripetal actin flow were simulated until the myosin distribution and the flow pattern reached steady state (see Text S1). Then, the boundary mesh was advanced/retracted in the locally normal direction with the rate , where is the normal component of the simulated flow pattern at the cell boundary and is the rate of actin polymerization. After the shape change, the lamellipodial area was remeshed and the density and flow simulations were repeated until the iterations converged to a stable shape. In the first half of the movie, the adhesion drag coefficient ζ = 0.04 nNs/μm4 and the cell converges to a round shape. Halfway through the movie, ζ increases to 0.2 nNs/μm4 and the shape evolves to a more elongated shape. The direction and magnitude of local actin network movement with respect to the underlying substrate is indicated by color-coded arrows; hot colors correspond to faster flow.