How does the concept of a circle relate to cyclins?

The progression of a cell by the cycle of cell is regulated by the protein family Cyclic

Explanation:

In the year 1982, Cyclin was located by Timothy Hunt as a family of proteins which has a vital function in the progression of a cell. CDK enzymes or 'cyclin dependent kinase' gets activated by it that synthesizes the cycle of the cell. The concentration of this protein moves in a cyclic way in the cell cycle. No enzymatic function is seen in them but it aims at CDK's different location.