The STRING database integrates known and predicted protein-protein interactions, including direct (physical) and indirect (functional) associations derived from genomic context, high-throughput experiments, co-expression and literature mining. It covers over 373 proteomes and draws on data from curated databases, textmining and computational prediction methods to provide a global network of protein interactions. STRING uses a scoring scheme to assign probabilities to interactions based on different lines of evidence and benchmarking against a gold standard reference set.