Table 1. The rules of interaction of the main elements involved in the fission yeast cell cycle regulation.

Parent node	Daughter node	Rule of activation (comments)	Rule of inhibition (comments)
Start node	Starter Kinases (SK): Cdc2/Cig1, Cdc2/Cig2, Cdc2/Puc1	Start node works as an indicator of mass of the cell and activates Start Kinases (SK) Cdc2/Cig1, Cdc2/Cig2, Cdc2/Puc1, +1[9]
SK	Ste9, Rum1		Phosphorylate, thereby inactivate, −1 [9], [25]
Cdc2/Cdc13	Cdc25	Cdc25 is phosphorylated thereby activated, +1 [9].
Wee1, Mik1	Cdc2/Cdc13*		Phosphorylate, inactivating, −1 [9]
Rum1	Cdc2/Cdc13, Cdc2/Cdc13*		Binds and inhibits activity, −1 [9].
Cdc2/Cdc13	Rum1		Phosphorylates and thereby targets Rum1 for degradation. −1 [9], [25]
Ste9	Cdc2/Cdc13, Cdc2/Cdc13*		Labels Cdc13 for degradation [25], [9], −1.
Cdc2/Cdc13*	Slp1	Highly activated Cdc2/Cdc13* activates Slp1, [24], [9] +1.
Slp1	Cdc2/Cdc13, Cdc2/Cdc13*		Promotes degradation of Cdc13, thereby the activity of Cdc2/Cdc13 drops −1 [9]
Slp1	PP	Activates, +1 [9]
PP (Unknown phosphatase)	Ste9, Rum1, Wee1, Mik1	Activates Rum1, Ste9, and the tyrosine-modifying enzymes (Wee1, Mik1) [9], +1
Cdc25	Cdc2/Cdc13*	Cdc25 reverses phosphorylation of Cdc2, thereby Cdc2/Cdc13* becomes active, +1 [9], [24]
Cdc2/Cdc13	Ste9		inhibits −1 [24]
PP	Cdc25		inhibits −1 [9]
Cdc2/Cdc13	Wee1, Mik1		inhibits −1 [24]
Cdc2/Cdc13*	Rum1, Ste9		Inhibits −1 [24]