Understanding of robustness for a basic system of cell cycle in yeast

This paper discusses a robustness analysis of cell cycle in yeast, which is one of eukaryotic cell cycles, and focuses on the understanding functions of Cdc25 and Weel proteins by using the Michaelis-Menten method. The robustness of the cell cycle is analyzed based on the sensitivity analysis for a mathematical model. From the first analysis result, it was shown that Cdc2 and Cyclin proteins have main roles for cell cycle in this model but the robustness is not high against perturbation on its parameters. By introducing Cdc25 and Weel proteins to the mathematical model, it was verified by the sensitivity analysis that the modified has higher level of robustnesses than the old model does. Numerical examples are shown to demonstrate the old model and the new model have almost identical cell cycle behaviors leaving robustness as a salient difference. Finally the difference of the Michaelis-Menten method and the Mass equation method are well understood.