Proteins that are involved in the regulation of the cell cycle and that show fluctuations in concentration during the cell cycle are called a. cyclins b. chromosomes c. atpases d. kinases e. kinetochores

Proteins that are involved in the regulation of the cell cycle and that show fluctuations in concentration during the cell cycle are called cyclins.  

Cyclin is a family of regulatory proteins that control the cell cycle by activating cyclin-dependent kinases. Cyclins are named like this because their concentration varies during the cell cycle. Their concentrations are tightly regulated, the peak of their concentrations is when their target protein is required for function.