Answer:
CDKs, or cyclin-dependent kinases, are present in the cell at a constant concentration throughout the entire cell cycle.
Explanation:
It is the concentration of cyclins that changes. When there are more cyclins in the cell, they will bind to more of the CDKs and form more cyclin-CDK complexes with do the real regulating. So if you're asking about cyclin concentration, that depends on what kind of cyclin you're dealing with because different ones are produced and broken down at different points. For example, the M cyclin helps regulate mitosis, so it is at its highest concentration during mitosis and is degraded shortly after, before being produced all over again the next time S or G2 phase rolls around.
Remember though that the CDK level stays the same; the thing that changes is the changes is the cyclins that activate it/.
