We have applied new experimental and computational approaches to understand the mechanical events of adherent cells. While the extensive use of flexible substrates has lead to excellent understanding of traction forces, introduction of long polymers into the cytoplasm has started to shed light on weak gradients of forces generated by the cortex. In addition, a top-down mathematical model has been developed to simulate the control circuit that coordinates protrusions and retractions. The model is capable of generating experimentally measurable parameters, which in turn allows the use of optimization algorithms to match the model with observations, and to provide insights into how a unified feedback mechanism might generate a wide range of behaviors.