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In cellular biology, labile cells are cells that multiply constantly throughout life.〔(Encyclopædia Britannica Online: labile cell )〕 They spend little or no time in the quiescent G0 phase of the cell cycle, but regularly perform 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. 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.〔(How chemotherapy works ) at cancerhelp.org〕 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, 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.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Labile cell」の詳細全文を読む スポンサード リンク
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