Why Is G1 considered to be a significant regulatory period?

G1-phase:

1. The intermediate phase between the end of mitosis and the S-phase (DNA replication phase) is the G1 phase.
2. It is the phase where the cell prepares for DNA replication, and different proteins required for the replication process are synthesized.
3. G1gets the cells committed either to continued division or exit the cell cycle.
4. During unfavorable conditions for growth, or when there are inhibitory signals revived from other cells, cells can pause for prolonged durations in the G1 or even enter a long non-dividing state, which is known as the G0 phase.
5. It is impossible for those cells present in the non-dividing, terminally differentiated condition to reenter the cell cycle.
6. These are the cells originating in the cell population referred to as the stem cells that retain the capability to division.