1. Not all cells move through the ________ ________ at the same rate.
2. Experiments show that the controls on cell ______________ and cell __________ can be turned on and off.
3. Tim Hunt and Mark Kirschner discovered that cells in mitosis contained a protein that when injected into a nondividing cell, would cause a ____________ spindle to form.
4. ____________ regulate the timing of the cell cycle in eukaryotic cells.
5. There are ___________ types of regulatory proteins.
6. ____________ ____________ allow the cell cycle to proceed only when certain process have happened inside the cell.
7. External regulators direct cells to ____________ up or ____________ down the cell cycle.
8. Growth ____________ are among the most important external regulators.
9. Molecules found on the surfaces of _______________ cells often have an opposite effect, causing cells to slow down or stop their cell cycles.
10. ____________ is a disorder in which some of the body's own cells lose the ability to control growth.
11. Cancer cells do not ____________ to the signals that regulate the growth of most cells.
12. Masses of cancer cells form ____________ that can damage normal tissues. nnn
13. The Various forms of cancer have many causes, including ____________________, ___________________, and even ____________________
14. An astonishing number of cancer cells have a ____________ in a gene called p53.
15. Cancer is a disease of the _________ __________.
16. Stem cells are unspecialized cells that have the potential to _______________.
17. Researchers have found that _______________ of stem cells can reverse the effects of brain injuries in mice.
18. Embryonic stem cell research is highly _______________.