Yes, many cells can leave G0, but not all of them do.

What G0 Actually Is

  • G0 is a quiescent or “resting” state where a cell has exited the active cell cycle and is not dividing, but is still metabolically active.
  • Cells can stay in G0 for days, years, or even for the rest of the organism’s life, depending on the cell type.

When Cells Can Leave G0

  • Some cells are only temporarily in G0 and can re‑enter G1 (and then the rest of the cell cycle) when they receive the right external signals, such as growth factors or mitogens.
  • Examples: many liver cells and some other tissue cells can leave G0 and start dividing again after injury or when more cells are needed for normal turnover.

When Cells Stay in G0 Permanently

  • Some highly differentiated cells, like mature neurons and cardiac muscle cells, enter G0 and essentially stay there for life; they do not normally divide again.
  • These cells are still active in their function (conducting nerve impulses, contracting muscle) but are considered permanently post‑mitotic.

Molecular View (Brief)

  • Exit from G0 involves re‑entering G1 and restarting the cell‑cycle machinery, including cyclin–CDK activity that inactivates the Rb protein to drive the G1→S transition.
  • Specific complexes, such as cyclin C–CDK3, help phosphorylate Rb at key sites (e.g., S807/811) and are important for G0 exit.

Simple Takeaway

  • Many cells: Yes, they can leave G0 if stimulated (e.g., by growth factors, injury signals).
  • Some specialized cells: No, they are essentially “locked” in G0 and do not divide again under normal conditions.

Information gathered from public forums or data available on the internet and portrayed here.