Cells can pause in G1 when DNA is damaged, and can pause in S when there are replication errors. Indicate whether the mechanism below applies to a G1 arrest, an S-phase arrest, both types of arrest, or neither
A. p53 activates the transcription of a Cdk inhibitor.
B. Cyclins are phosphorylated and destroyed.
C. Cdk is unable to phosphorylate its substrates.
D. The Cdc25 phosphatase is inhibited.
A. G1 arrest
B. neither
C. both
D. S-phase arrest
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