Abstract
The central spindle regulates cleavage furrow formation and cytokinesis and is composed of antiparallel microtubules bundled by microtubule-associated proteins and kinesin motors. One key protein in the central spindle is a Rho family GTPase-activating protein, CYK-4/MgcRacGAP, whose target is the subject of two new studies that arrive at divergent models.