Fig. 1

Dynamics of the cell cycle with its associated cyclin-cyclin dependent kinase complexes. The interphasic cells, at their G₁ phase, are diploids (2n). As to prepare the cell for an eventual division, its genetic material, i.e., DNA, is replicated during the S phase. Thus in the later S phase and G₂ phase, the cell has a doubled DNA (4n). The mitotic division occurs from Prophase through Telophase, as shown in the figure. At the end of mitosis, there is a formation of two daughter cells. G₀ symbolizes a quiescent state through which cells could eventually go. The cyclin-cyclin-dependent kinases reflected on the figure are checkpoints of the cell cycle, each of which could eventually determine the cell’s fate with respect to the presence and/or absence of mitogens and growth factors