Module 9: Figure cytokinesis
Control of cytokinesis.
Cytokinesis begins at telophase, and is driven by formation of an actomyosin contractile ring and by a process of vesicle fusion. Contraction of the ring squeezes the cell such that it finally cleaves in two. Formation of the contractile ring is controlled by the spindle midzone complex that forms in the region where the polar microtubules intersect. One of the components of this complex is MgcRacGAP, which is a GTPase protein that controls the activity of RhoA. The latter has a central role in regulating both the formation of the contractile ring and in the activation of the ring during cytokinesis (see the text for further details).