Constantly fast dividing cells

Overview
In cellular biology, constantly fast dividing cells are cells that spend little or no time in the quiescent G0 phase of the cell cycle, but regularly performs cell division.

This is the case for only a minority of cells in the body. Constantly dividing cell types include skin cells, cells in the gastrointestinal tract and blood cells in the bone marrow.

Many more types of cells in the body are constantly or regularily dividing, albeit at a very slow rate.

It is mainly not the segments of the cell cycle that go faster (i.e. G1 phase, S phase, G2 phase and M phase), but rather a short or absent G0 phase.

Hazards
Constantly dividing cells have a higher risk of becoming malignant and develop cancer, dividing uncontrollably. This is why, on the other hand, muscle cancer is very rare, although constituting ~50% of body weight, since muscle cells are not constantly dividing cells.

In addition, cytotoxic drugs, used in treatment of cancer, work by inhibiting the proliferation of dividing cells, with the malignant cells as the desired target. However, this has the adverse effect of also striking against the cells normally dividing in the body, and thus impairing normal body function of skin, GI tract and bone marrow.