Physics of cell motility: dynamic networks and flexible membranes Wolfgang Lösert U. of Maryland Motion of cells in response to external signals is cruical for many biological processes, from wound healing to the spread of cancer. I will discuss two of the physical processes that can generate the forces needed for cell motion: Dynamic changes in the scaffolding of filaments (actin, tubulin, and intermediate filaments) that give a cell mechanical strength, and deformations of cell membranes. I will introduce a toy model of dynamic self-assembling filaments that recovers the key properties of e.g. tubulin. Experimentally we use two photon confocal microscopy for 3D imaging and a holographic laser tweezer for multipoint mechanical measurements of both filament networks and membranes. Recent experiments indicate that spatial gradients in network properties can generate strong directional forces on objects embedded in the network.