Review Volume 3, Issue 2 pp 94—101

Figure 2. Two types of quiescence. (A) Simple quiescence. Cells are arrested due to lack of growth stimulation (left panel). Addition of growth factors causes proliferation (right panel). (B) Locked quiescence. Differentiated cells are put on the brakes, to avoid undesired proliferation. Mild stimulation of such cells causes functional responses. Excessive stimulation causes physiological senescence.