18. Which of the following is NOT a checkpoint that controls the progression of the cell cycle? (A) Cyclins and cyclin-dependent kinases are proteins that are responsible for advancing a cell through the phases of the cell cycle. (B) The G2 checkpoint checks for DNA damage and determines if all of the DNA is replicated. (C) The metaphase checkpoint determines if all chromosomes are attached to the spindle apparatus. (D) Cytokinesis involves the formation of cleavage furrow to separate the cells. (E) The restriction point determines if conditions are favorable for cell division and if the DNA is undamaged.