Inactivation of Clp1 and PP2APab1 does not show additive effects upon phosphorylation of Wee1 or Cdc25. (A, C) Western blots of Wee1, Cdc25, Cdc13, and Cdk1 inhibitory phosphorylation during the cell cycle in clp1Δ and pab1Δ clp1Δ cells synchronized by centrifugal elutriation. A background band was used as a loading control. (B, D) A fluorescence microscopy assay using DAPI and calcofluor was used to determine the percentage of binucleated cells and cells undergoing septation.