Final answer:
Rho GTPases are proteins that regulate actin polymerization, controlling the assembly of actin monomers into polymers. They play a crucial role in cell structure and motility.
Step-by-step explanation:
Actin polymerization is regulated by proteins called Rho GTPases. Rho GTPases are enzymes that control the assembly of actin monomers into polymers by activating other proteins involved in actin polymerization. They play a crucial role in cell structure and motility. For example, Rho GTPases promote the formation of stress fibers in the cytoskeleton, which are bundles of actin filaments that provide structural support to the cell and are involved in cell migration. They also regulate the formation of filopodia and lamellipodia, which are finger-like protrusions on the cell surface, important for cell movement and sensing the environment.