Figure 9. Strains lacking three distinct mechanisms for controlling the interaction of the CPC with spindle microtubules fail to show an additive growth defect.

Equivalent 10-fold serial dilutions of the indicated strains were spotted onto YPAD medium and YPAD medium containing the indicated concentrations of benomyl and then incubated for 2 days at 26°C. ipl1-2A and ipl1-2E are alleles in which Cdc28 phosphorylation sites Ser-50 and Ser-76 in Ipl1 have been substituted by either alanine or glutamate residues respectively, while sli15-335A and sli15-335D have either alanine or aspartate substituted for the key serine residue in Sli15 that is phosphorylated by Cdc28 [18].