Restriction point

The restriction point is a G1 phase checkpoint in the cell cycle of animal cells. Cells that progress through this point are committed to enter S phase, where DNA 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 G0 phase, a quiescent stage. Lack of growth factors causes some cells to arrest at the restriction point.

Yeast cells contain a similar checkpoint, the start point.

The Restriction Point was discovered in the 1970s by the American biochemist Arthur Pardee