Both cell growth (cell mass increase) and progression through the cell division cycle are required for sustained cell proliferation1. Proliferating cells in culture tend to double in mass before each division2, but it is not known how growth and division rates are co-ordinated to ensure that cell size is maintained1,
3,
4,
5. The prevailing view is that coordination is achieved because cell growth is rate-limiting for cell-cycle progression6,
7,
8,
9,
10. Here, we challenge this view. We have investigated the relationship between cell growth and cell-cycle progression in purified rat Schwann cells, using two extracellular signal proteins that are known to influence these cells11,
12,
13. We find that glial growth factor (GGF) can stimulate cell-cycle progression without promoting cell growth. We have used this restricted action of GGF to show that, for cultured Schwann cells, cell growth rate alone does not determine the rate of cell-cycle progression and that cell size at division is variable and depends on the concentrations of extracellular signal proteins that stimulate cell-cycle progression, cell growth, or both.
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REFERENCE Oligodendrocytes Nature Encyclopaedia of Life Sciences
