The NCI-Nature Pathway Interaction Database
Biomolecular interactions and cellular processes assembled into authoritative human signaling pathways. The NCI-Nature Pathway Interaction Database is publicly funded via the US government National Institutes of Health the data are free to use without restriction.
BioCarta Pathways catalogs and summarizes resources providing information for over 120,000 genes from multiple species. The BioCarta.com site is being provided by BioCarta, Inc. Information on Biocarta is not freely available. Check Terms and Conditions section in Biocarta website for use.
The Gene Ontology (GO) project is a collaborative effort to address the need for consistent descriptions of gene products in different databases. The GO consists of three ontologies: biological processes, cellular components and molecular functions in a species-independent manner.