Cell cycle
There are 4 checkpoints given in different phases of the cell cycle:
G0: Resting state. Given only when the cell is not prepared to divide. It takes place at the end of the G1 phase.
G1 checkpoint: It takes place in the same moment as the G0, this is a check for nutrients, growth factors (molecular signs), and DNA integrity.
G2 checkpoint: It takes place at the end of the G2 phase, to check if the cell size is correct and the DNA replication was correctly done.
Metaphase checkpoint: At the end of the metaphase. Here is checked the chromosome spindle attachment and chromosome alignment to the equatorial plate.