1. A method of identifying target proteins for drug therapies comprising: obtaining proteome data defining proteins and proteins interactions for an organism to be targeted; storing said proteome data in the form of network data defining a plurality of nodes and a plurality of links between said nodes; processing said stored network data to determine for each of said nodes a value, wherein said determined values are indicative of the proportions of paths between said nodes in said network which pass through each of said nodes relative to paths between said nodes in said network which do and do not pass through each of said nodes; associating nodes with said determined values for said nodes; and outputting as data identifying target proteins, data identifying proteins corresponding to nodes associated with values above a threshold.