Consider two mammalian cells, one in G1 and the other in G0 (stationary) phase. If they are stimulated to pass the restriction point by the addition of an extracellular proliferation signal, but the signal is then immediately removed, what would you expect to happen?A) Both cells will replicate their DNA.B) Only the G1 cell will replicate its DNA.C) Only the G0 cell will replicate its DNA.D) Only the G1 cell will start to replicate its DNA, but will stop halfway through the replication and will not reach G2.E) Neither of the cells will replicate their DNA.

G0 phase can be described as a phase in which the cell goes into a resting phase. It does nor prepare to replicate itself. A cell might enter G0 phase because it might not have sufficient nutrition to under go the process of replication or some specialized cells like the neuronal cells are fully differentiated so they do not require to be replicated.

An extra proliferation signal will trigger the cell to move pass the restriction point and to start dividing. And hence, both cells will start to replicate their DNA.