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. Author manuscript; available in PMC: 2014 Nov 26.
Published in final edited form as: Cytoskeleton (Hoboken). 2012 Oct 9;69(11):919–930. doi: 10.1002/cm.21071

Figure 1. Rho GTPase signaling at the central spindle.

Figure 1

Active Rho GTPases form spatially distinct activity zones within dividing animal cells (upper). GTP-bound RhoA localizes to the division plane. GTP-bound Rac*, on the other hand, has been found to be enriched in the polar regions of the cell and excluded from the division plane. Equatorial Rho family GTPase activity is regulated by GEFs and GAPs, many of which localize to the microtubule-rich central spindle (lower, close-up view). Together, MKLP1 and MgcRacGAP form a complex (called Centralspindlin) that participates in bundling of central spindle microtubules. *The polar enrichment of active Rac during cytokinesis has only been shown in cultured mammalian cells. **Cdc42 activity has been shown to be enriched in the polar region of one side of the cell during asymmetric cell divisions but has not been closely examined during symmetric divisions.