Reactome - a knowledgebase of human biological pathways Reactome is a manually curated knowledgebase, created and peer-reviewed by experts in their field. Its robust data model describes life processes ranging from metabolism to signal transduction and the cell cycle. As of release 28, Reactome contains 3700 human proteins in 3200 reactions. Data is cross-referenced to publicly available web-based informatics resources. Reactome features the SkyPainter tool for analysis of high-throughput datasets, and the Mart query and data retrieval tool.