Those two steps are the G1 and G2 checkpoints.
One important step during this phase sees CKI-p16 inhibit CDK4/6; when this is overcome, cyclin E interacts with CDK2 to being the next step of this phase. Another step in this phase sees MPF activate CDK to begin the phase after this one. Those two steps are the G1 and G2 checkpoints. Another stage that occurs during this period sees the formation of two sister chromatids and is known as S phase. For 10 points, name this phase that occupies the majority of the cell's life cycle, the stage in which there is no cell division through mitosis.
One important step during this phase sees CKI-p16 inhibit CDK4/6; when this is overcome, cyclin E interacts with CDK2 to being the next step of this phase.
interphase