Evidence that Aurora B is implicated in spindle checkpoint signalling independently of error correction This is an open-access article distributed under the terms of the Creative Commons Attribution Noncommercial No Derivative Works 3.0 Unported License, which permits distribution and reproduction in any medium, provided the original author and source are credited. This license does not permit commercial exploitation or the creation of derivative works without specific permission. Fidelity of chromosome segregation is ensured by a ten-sion-dependent error correction system that prevents stabilization of incorrect chromosome–microtubule at-tachments. Unattached or incorrectly attached chromo-somes also activate the spindle assembly checkpoint, thus delaying mitotic exit until all chromosomes are bioriented. The Aurora B kinase is widely recognized as a component of error correction. Conversely, its role in the checkpoint is controversial. Here, we report an analysis of the role of Aurora B in the spindle checkpoint under conditions believed to uncouple the effects of Aurora B inhibition on the checkpoint from those on error correc-tion. Partial inhibition of several checkpoint and kineto-chore components, including Mps1 and Ndc80, strongly synergizes with inhibition of Aurora B activity and dra-matically affects the ability of cells to arrest in mitosis in the presence of spindle poisons. Thus, Aurora B might contribute to spindle checkpoint signalling independently of error correction. Our results support a model in which Aurora B is at the apex of a signalling pyramid whose sensory apparatus promotes the concomitant activation of error correction and checkpoint signalling pathways.