In eukaryotic cells, septins have diverse roles in cytoskeletal dynamics, cell division, and vesicle trafficking. During cilia formation, septins detect the outward curvature of the plasma membrane and interact to form a diffusion barrier at the base of the cilium. This barrier allows the selective transport of solute particles between the cilium and the cytoplasm. During cell division, septins identify the cleavage furrow in the plasma membrane and form a septin ring around it. The ring then recruits structural proteins, like microfilaments and myosin II filaments to form the contractile ring for cytokinesis. In neurons, septins function as microtubule-associated proteins for vesicle trafficking. They bind with microtubules and regulate the movement of cargo transport by motor proteins including kinesins.