Abstract: Protein－protein and protein－DNA interactions in living cells constitute molecular dynamic networks that govern various cellular functions. Based on recent studies of budding yeast and other related literature, we have established the protein network governing the cell cycle and life cycle processes. Here we report our dynamical analysis of the cell－cycle network of budding yeast using a discrete two－state model. Our study reveals important properties of the network: (1) almost all (~94%) initial protein states evolve to the stationary state G1, making it a global attractor; (2) the dynamical paths to G1 for these initial states are through the cell－cycle sequence, making it a globally attracting trajectory.