- Restriction point
The

**restriction point**is a G_{1}phase checkpoint in thecell cycle ofanimal cells. Cells that progress through this point are committed to enterS phase , whereDNA synthesis and replication will occur. If a cell is not ready, or external conditions are not appropriate for the S phase, then the cell may enter G_{0}phase, a quiescent stage. Lack ofgrowth factor s causes some cells to arrest at the restriction point.Mutation s in factors contributing tocell cycle arrest at the restriction point are thought to be the main contributors ofcancer [*Cancer Cell Cycles, Charles J. Sherr, Science, 6 December 1996*]Yeast cells contain a similar checkpoint, theSTART point .The Restriction Point was discovered in the 1970s by the American biochemist

Arthur Pardee **ee also***

Mitosis

*Cell Cycle **References**

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