In this book the author present an analisys she performed on networks of phosphatases. The research was performed using a graph representation to outline the relation of each protein with the pathways in which it is annotated. The annotation of a phosphatase in a pathway corresponds to the evidence that the enzyme is involved in the corresponding biological process; the graph representation outlines the relation of pathways that share the same protein phosphatase as they appear connected in the network. The corresponding graph has been used to apply a clusterization algorithm to see if it was possible to identify groups of pathways that are characterized by the fact that they share a higher number of phosphatases than average. Dealing with functional correlation focused on protein phosphatases, the research activity was also conducted with the scope of illustrating a new possible approach to investigate the functional correlation between couples of proteins. As such, the last part of this book describes a new data mining methodology that is proposed to help when dealing with the hard problem of the interpretation of experimental outcomes from high throughput experiments.