Two important checkpoints that regulate the cell's progression through the cell cycle occur in the and phases of the cell cycle. see section 12.3 (page 264) .

Two important checkpoints that regulate the cell's progression through the cell cycle occur in the G1 and G2 phases of the cell cycle.

G1 (restriction) checkpoint  - the cell becomes committed to entering the cell cycle

G2 checkpoint - chromosomes have replicated successfully.