Cells move by the action of specific proteins or small molecules that assemble and interact, constituting a dynamic network called the cytoskeleton. Actin, one of the major components of eucaryotic cells, exists as filaments (semi-flexible polymers) or as monomers. Local assembly of the actin network leads to cell movement as well as to the propulsion of objects like bacteria or liposomes within cells. In order to understand the force generated for this propulsion, we use biomimetic experimental systems that allow for the control of physical parameters. We show evidence for the role of elasticity in the propulsion mechanism.