The mechanism of action and interaction of regulators of cell replication.

The oscillator concept of the cell cycle suggests that regulation of replication is achieved through a switch-like process. This is triggered when the values of parameters governing the behaviour of an intracellular control system exceed thresholds (bifurcations) which separate oscillatory and non-oscillatory (or damped oscillatory) modes of operation. On this basis it becomes possible to explain (a) how a given regulator can have diverse effects, (b) how distinct agents can have similar responses and (c) how various agents interact when controlling replication. The relevance of the malignant transformation is also briefly discussed.