During cell division, chromosome movement and cytokinesis must be precisely coordinated to ensure accurate segregation of chromosomes to daughter cells. Baum and colleagues report the existence of a signalling pathway that triggers polar relaxation — that is, the local softening, at cell poles, of the otherwise rigid actomyosin cortex — which enables cell elongation during anaphase and orderly cell division. Live-cell imaging revealed that actin was cleared from cell poles before furrow formation at the cell equator in Drosophila melanogaster and in human cells. Loss of F-actin and cortical relaxation occurred in response to chromatin coming closer to the poles at mid-anaphase. The authors found that this was dependent on protein phosphatase 1 and its regulatory subunit SDS22, which localize at kinetochores and induce the dephosphorylation and inactivation of ezrin–radixin–moesin proteins, which link actin to the plasma membrane, at the cell poles.