2009 Volume 44 Issue 2 Pages 135-138
During cytokinesis, the final step of cell cycle, actin and myosin fibers assemble at the equatorial cell cortex and form the contractile ring. The motor activity of myosin II is believed to generate constriction force that cleaves a parent cell into two daughter cells. Anaphase microtubules provide the specification signal for the contractile ring, yet the nature of the signal remains unclear. In this review, I discuss how microtubules specify the contractile ring. I show that the small GTPase Rho and a complex of Rho regulators (ECT2 RhoGEF, MgcRacGAP, MKLP1 kinesin) act as a cleavage signal that specifies the contractile ring. I also discuss the visualization of the cleavage signal generated by anaphase microtubule, using live cell imaging techniques.