Formation of the mitotic spindle involves a tightly regulated series of coordinated events that ultimately leads to chromosome segregation and cytokinesis. On p. 435, Stephen Huisman and colleagues investigate the role of the essential cell cycle kinase Cdc28-Clb5 in polarity of the mitotic spindle and describe a novel role for spindle pole body component Spc110 in the regulation of spindle morphogenesis in yeast. The authors performed a genetic screen to identify targets of Cdc28-Clb5 kinase involved in spindle polarity and identified a truncated version of Spc110. The truncated version, Spc110Δ13, can suppress the lethal phenotype of the cdc28-4 clb5Δ strain. Cdc28-Clb5 localises to spindle poles and intranuclear microtubules, which is consistent with a role in spindle morphogenesis. The authors find that the Clb5-dependent kinase phosphorylates Spc110 in a cell-cycle-dependent manner at two CDK consensus sites, which is crucial for correct spindle integrity. Their data support a model whereby phosphorylation of spindle pole body components by CDK temporally controls mitotic spindle assembly and polarity at the level of astral microtubule organisation.