Much of what is known about the function of cyclin and Cdk was learned by mutations in yeast. One yeast mutant is known as wee1. As its name implies, this yeast mutant never achieves full size. It divides continuously without allowing time for the cells to grow to their normal size. The defect is caused by inactivation of a gene that encodes a protein kinase. What might be a possible role for this kinase in normal wild-type yeast?