localization during cytokinesis and cellularization is dependent on its association with anillin. The direct interaction between anillin and septins was first shown by the interaction seen between Xenopus anillin and a minimal reconstituted heterooligomer of human septins 2, 6, and 7. The ability of anillin to bind to septins is dependent on the C-terminal domain, which contains a terminal PH domain and an upstream sequence known as the “Anillin Homology” (AH) domain. Rho The AH domain of human anillin is essential for its interaction with RhoA. Depletion of RhoA halts contractile ring assembly and ingression, whereas, anillin depletion leads to a less severe phenotype when the contractile ring forms and ingresses partially. Depletion of anillin in Drosophila spermatocytes greatly reduces the localization of Rho and F-actin to equatorial regions. Ect2 Anillin interacts with Ect2, further supporting the idea that anillin stabilizes RhoA localization since Ect2 is an activator of RhoA. Independent of RhoA, the interaction between anillin and Ect2 occurs. This interaction is essential of the GEF activity of Ect2 and requires the AH domain of anillin and the PH domain of Ect2. Cyk-4 Drosophila anillin interacts with Cyk-4, a central spindle protein, indicating that anillin may have a role in determining the division plane during cytokinesis. In anillin-depleted larval cells, the central spindle does not extend to the cortex. Human anillin-depleted cells show improperly positioned and distorted central spindles. Microtubules Anillin was first isolated from Drosophila by harnessing its interactions with both F-actin and microtubules. Furthermore, anillin-rich structures that form after Latrunculin A treatment of Drosophila cells localize to the plus-ends of microtubules. The interaction between anillin and microtubules suggest that anillin may serve as a signaling factor to relay the position of the mitotic spindle to the cortex to ensure appropriate contractile ring formation during cytokinesis. Regulation Anillins in metazoans are heavily phosphorylated; however, the kinases responsible for the phosphorylation are unknown at the present time. In humans and Drosophila, anillins are recruited to the equatorial cortex in a RhoA-dependent manner. This recruitment is independent of other cytoskeletal Rho targets such as myosin, F-actin, and Rho-kinase. It has been observed that anillin proteolysis is triggered after mitotic exit by the Anaphase Promoting Complex (APC). Most anillins can be sequestered to the nucleus during interphase, but there are exceptions – Drosophila anilins in the early embryo, C. elegans ANI-1 in early embryos, C. elegans ANI-2 in oogenic gonads, and