Updated project metadata. Given that Cdc14 enzymes are so highly conserved, we questioned whether budding yeast Cdc14 could really have such a different influence on Cdk site dephosphorylation. We used quantitative phosphoproteomics to directly measure the in vivo specificity of budding yeast Cdc14 and found that it very selectively dephosphorylates a distinct sub-class of Cdk sites and does not catalyze widespread Cdk site dephosphorylation as widely believed.