Concentration Cell Cycle and Cytoskeleton Class Problems G1 S G2 M Based on the above description, draw the relative concentrations of the Cyclins at each point of the cell cycle on the graph above. How are the concentrations of these cyclins controlled? Cyclin/CDK complexes phosphorylate downstream proteins, which results ultimately in transcription. What types of genes do you think are transcribed by each cyclin/CDK complex?