The cells in G0 phase do not go through mitosis whatsoever. These cells only do what they are initially suppose to do, and do not prepare for a division. Many cells in your body are like this. Brain cells are in G0 phase and do not EVER replace itself. However, many cells may also trigger its phase from G0 phase to G1 phase when more cells are needed. When a liver is critically damaged, the liver cells are triggered back to G1 phase to replenish its lost cells.