单项选择题
Which of the following statements about CDK and cyclin is wrong? ()
A．The activation of CDK must be based on binding to cyclin
B．As long as cyclin binds to CDK, the latter can exhibit protein kinase
activity
C．The amino acid sequence of CDK bound by cyclin is conserved
D．Different cyclins are expressed at different phases of the cell cycle
and can bind to different CDKs
E．Cyclin D mainly binds to CDK4 and CDK6 and participates in G1/S phase
transformation
,则
的取值为（ ）。
