- Restriction point
The restriction point is a G1 phase checkpoint in the
cell cycleof animalcells. Cells that progress through this point are committed to enter S phase, where DNA synthesisand replication will occur. If a cell is not ready, or external conditions are not appropriate for the S phase, then the cell may enter G0 phase, a quiescent stage. Lack of growth factors causes some cells to arrest at the restriction point. Mutations in factors contributing to cell cyclearrest at the restriction point are thought to be the main contributors of cancer[Cancer Cell Cycles, Charles J. Sherr, Science, 6 December 1996] Yeastcells contain a similar checkpoint, the START point.
The Restriction Point was discovered in the 1970s by the American biochemist
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