Microfilaments
Microfilaments, also known as actin filaments, are the thinnest filaments of the cytoskeleton and are composed of linear polymers of G-actin subunits. Microfilaments are able to generate force when the growing end pushes up against a barrier; the type of barrier varies, but one example is the cell membrane. Microfilaments also act as tracks for the transportation of myosin molecules to follow and “walk” along. Actin structures are regulated by the Rho family, small GTP-binding proteins including Rho itself for contractile acto-myosin filaments, Rac for lamellipodia and Cdc42 for filopodia.