Which of the following statements about cell-cycle regulation is correct?
A. Cyclins are regulatory nucleotides in the cell cycle.
B. Cyclin-Cdk complexes phosphorylate carbohydrates.
C. A decrease in p27 protein causes a nondividing cell to resume division.
D. Protein kinases break down and rebuild the nuclear membrane.
E. Cytokinins stimulate growth and wound healing in animal cells.