Abstract: ABSTRACT: Reactome (www.reactome.org), an online curated resource for human pathway data, provides infrastructure for computation across the biological reaction network. We use Reactome to infer equivalent reactions in multiple non-human species, and present data on the reliability of these inferred reactions for the distantly-related eukaryote S. cerevisiae. Finally, we describe the use of Reactome both as a learning resource and as a computational tool to aid in the interpretation of microarrays and similar large-scale data sets.