Claim: Protein Cyclin E1 forms a complex with, and functions as, a regulatory subunit of CDK2 ( cyclins function as regulators of CDK) which activity is required for cell cycle G1/S transition; different cyclins exhibit distinct expression and degradation patterns which contribute to temporal coordination of each mitotic event.
Evidence: G1/S-specific cyclin-E1 is a protein that in humans is encoded by the CCNE1 gene. This cyclin forms a complex with and functions as a regulatory subunit of CDK2, whose activity is required for cell cycle G1/S transition. Cyclins function as regulators of CDK. Different cyclins exhibit distinct expression and degradation patterns which contribute to the temporal coordination of each mitotic event.