This interactive module explores the phases, checkpoints, and protein regulators of the cell cycle. The module also shows how mutations in genes that encode cell cycle regulators can lead to the development of cancer. Toggle between two different views of the cell cycle by pressing the text in the center of the graphic. The “Cell Cycle Phases” view describes the cell cycle phases and checkpoints, and includes illustrations of the cell’s chromosomes. This view is appropriate for all levels of high school biology. The “Cell Cycle Regulators and Cancer” view explains the protein regulators, their roles in cell cycle progression, and how mutated versions can lead to cancer. This view may be more appropriate for AP/IB Biology and introductory college biology.