Mitotic and endomitotic cycling in early megakaryocytes. Progenitors that will become polyploid proceed through anaphase and then regress their cleavage furrows and re-enter G1 as 4N cells. Aurora B kinase is shown in orange, localized to kinetochores in metaphase, the spindle midzone in anaphase, and the midbody in telophase. Professional illustration by Marie Dauenheimer.