Aurora B kinase is active in telophase of endomitosis. (A) MKs were stained for tubulin (α and β, green), phospho-T232-Aurora B (red), and DNA (blue). Phosphorylated Aurora B was present in the midbody of dipolar mitotic cells. For multipolar endomitotic cells, phosphorylated Aurora B was essentially detected in late telophase midbody (arrowhead). (B) MKs were stained for tubulin (α and β, green), phospho-Ser387-MgcRacGAP (red), and DNA (blue). During telophase, phospho-Ser387-MgcRacGAP was strongly enriched in the midbody for dipolar mitosis. A similar labeling pattern was observed for multipolar endomitosis (arrowhead). Scale bars represent 10 μm.