Protein phosphorylation is a widespread cellular process, and simplistic linear pathway models of kinase signaling likely under-represent the complexity of in vivo pathways. The recent massive increase in information available through protein interaction databases now allows construction of in silico models of protein networks that are underpinned by evidence from real biological systems. By combining protein phosphorylation data with current databases of protein-protein and kinase-substrate interactions, sophisticated models of intracellular protein phosphorylation signaling can be constructed for a system of interest. The kinase interaction network can be visualized, analyzed by graph theory, and investigated for hypotheses that are not otherwise obvious.