Answer
True
Work Step by Step
Serine/threonine kinases belonging to the cyclin-dependent kinase (Cdk) family are essential for controlling the cell cycle. The presence of a bound cyclin controls the activity of Cdks by activating the kinase domain of the Cdk protein. Yet, the Cdk's enzymatic activity is also controlled by the phosphorylation of particular protein residues, which can either activate or inhibit the kinase activity.
The statement is true.
