Figure 3. Model for the collaboration between Aurora B and Polo kinases in the regulation of kinetochore-microtubule attachments. (A) Aurora B (red) phosphorylation of kinetochore subunits promotes the detachment of kinetochores that are not under tension (orange arrow). Polo (yellow) at the kinetochore promotes kinetochore attachment to microtubules (large green arrow). Aurora B also phosphorylates and activates Polo at centromeres, and possibly on kinetochores (or activated Polo relocalizes from centromeres to kinetochores). (B) Once amphitelic attachment is reached, tension stretches kinetochores, separating Polo on the outer kinetochore from Aurora B on the inner centromere. (C) The activation of Polo by Aurora B could facilitate the attachment/detachment cycle that takes place between kinetchores and microtubules in prometaphase.