The final event of the eukaryotic cell cycle is cytokinesis, when two new 
daughter cells are born. How the timing and execution of cytokinesis is 
controlled is poorly understood. Here, we show that downregulation of 
cyclin-dependent kinase (Cdk) activity, together with upregulation of its 
counteracting phosphatase Cdc14, controls each of the sequential steps of 
cytokinesis, including furrow ingression, membrane resolution and cell 
separation in budding yeast. We use phosphoproteome analysis of mitotic exit to 
identify Cdk targets that are dephosphorylated at the time of cytokinesis. We 
then apply a new and widely applicable tool to generate conditionally 
phosphorylated proteins to identify those whose dephosphorylation is required 
for cytokinesis. This approach identifies Aip1, Ede1 and Inn1 as cytokinetic 
regulators. Our results suggest that cytokinesis is coordinately controlled by 
the master cell cycle regulator Cdk together with its counteracting phosphatase 
and that it is executed by concerted dephosphorylation of Cdk targets involved 
in several cell biological processes.