Aurora B localization to mitotic centromeres, which is required for proper 
chromosome alignment during mitosis, relies on Haspin-dependent histone H3 
phosphorylation and on Bub1-dependent histone H2A phosphorylation--which 
interacts with Borealin through a Shugoshin (Sgo) intermediate. We demonstrate 
that Mps1 stimulates the latter recruitment axis. Mps1 activity enhances 
H2A-T120ph and is critical for Sgo1 recruitment to centromeres, thereby 
promoting Aurora B centromere recruitment in early mitosis. Importantly, 
chromosome biorientation defects caused by Mps1 inhibition are improved by 
restoring Aurora B centromere recruitment. As Mps1 kinetochore localization 
reciprocally depends on Aurora B, we propose that this Aurora B-Mps1 recruitment 
circuitry cooperates with the Aurora B-Haspin feedback loop to ensure rapid 
centromere accumulation of Aurora B at the onset of mitosis.