Mitotic Checkpoint Control in Fission Yeast

The cell cycle consists of a series of events that occur in a particular order. It has been proposed that this sequence is maintained in part through "checkpoints," controls that monitor early events and couple their completion to the onset of late events (Hartwell and Weinert 1989). In addition to maintaining dependencies characteristic of a normal cell cycle, checkpoint controls may also be important for cellular adaptation in response to adverse conditions (Weinert and Hart-well 1988). The intriguing possibility also exists that checkpoint controls may be altered during development and that their disruption may predispose cells to oncogenic transformation (Hartwell and Weinert 1989; Kung et al. 1990).