Studies of Rapidly Dividing Embryonic Animal Cells Revealed

Studies of rapidly dividing embryonic animal cells revealed:

A) a cyclic production of certain proteins in sync with the cell cycle.
B) a cyclic activation of protein kinases in sync with the cell cycle.
C) that the production of cyclin proteins is followed by activation of CDK enzymes.
D) that inhibition of protein production blocks mitosis.
E) All of these choices are correct.