“Negative” genes, such as Rb, suppress cell division. In normal cells, these anti-oncogenes, or tumor suppressor genes, provide the “brakes” to cellular proliferation, shutting down cell division when the cell receives appropriate signals. In cancer cells, these brakes have been inactivated by mutations. In cells with missing brakes, to use Bishop’s analogy again, the “stop” signals for mitosis can no longer be registered. Again, the cell divides and keeps dividing, defying all signals to stop. Both abnormalities, activated proto-oncogenes and inactivated tumor suppressors (“jammed
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