Answer:
External Factors:
The external factors which influence the cell cycle might be physical or chemical.
Physical factors: Physical signals involve the factors like when a cell touches another cell, it stops dividing.
Chemical factors: Chemical factors are the growth factors or growth proteins that trigger the cells to undergo the process of cell division.
Internal factors:
Kinases: Kinases are the proteins which determine whether the cell will undergo cell division or abort it.
Cyclins: When the signal is right for cell division, cyclins activate the kinases.
