 These studies unveil the important characteristics of the Sic1 CDK phosphorylation sites, which include priming sites, binding sites, degron pairs, distancing of phosphorylation sites, and relative site location.In addition, the studies also emphasize the influence of other factors on Sic1 phosphorylation, including the Cks1 phospho-binding pocket, cyclin docking motifs, and Cdk1 active site specificity.All of these mechanisms contribute to the dynamics of the sequence of events leading to Sic1 degradation and initiation of S-phase.