If You Mutate the Gene Encoding a Cdk Such That

If you mutate the gene encoding a Cdk such that Cdk protein product cannot bind to cyclin, what effect would you expect to see?

A) Cdk will be unaffected.
B) The cell cycle will be up-regulated, and the cells will proliferate.
C) Cdk will be inactive, so the target proteins will not be phosphorylated.
D) Cdk will be constitutively active, so the cell cycle will be unchecked.
E) Cdk will phosphorylate its target proteins regardless of the cell cycle.