Labile cell

In cellular biology, labile cells are cells that multiply constantly throughout life. The cells are alive for only a short period of time. Due to this, they can end up reproducing new stem cells and replace functional cells. Especially if the cells become injured through a process called necrosis, or even if the cells go through apoptosis. The way these cells regenerate and replace themselves is quite unique. While going through cell division, one of the two daughter cells actually becomes a new stem cell. This occurs so then that daughter cell can end up restoring the population of the stem cells that were lost. The other daughter cell separates itself into a functional cell in order to replace the lost, or injured cells during this process. Labile cells are one type of the cells that are involved in the division of cells. The other two types that are involved include stable cells and permanent cells. 
Each of these type of cells respond to injuries of the cells they occupy differently. Cell types that are thought to be cells that are constantly dividing include skin cells, cells in the gastrointestinal tract, and blood cells in the bone marrow. Acting as stem cells for these cell types. 
In labile cells, it is not a speed-up in the segments of the cell cycle (i.e. G1 phase, S phase, G2 phase and M phase), but rather a short or absent G0 phase that is responsible for the cells' constant division.
Hazards.
Constantly dividing cells have a higher risk of becoming malignant and develop cancer, dividing uncontrollably. This is why muscle cancer is very rare, even though muscle tissue accounts for ~50% of total body weight, since muscle cells are not constantly dividing cells, and therefore not considered labile.
In addition, cytotoxic drugs, such as alkylating antineoplastic agents, 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 hair, skin, GI tract and bone marrow.