Pathway Resources
Systems Biology Markup Language
The Systems Biology Markup Language (SBML) is a computer-readable format for representing models of biochemical reaction networks. SBML is applicable to metabolic networks, cell-signaling pathways, regulatory networks, and many others.

Systems Biology Graphical Notation
The Systems Biology Graphical Notation (SBGN) defines a comprehensive set of symbols with precise semantics, together with detailed syntactic rules defining their use and how diagrams of biochemical and cellular processes in systems biology are to be interpreted.

CellDesigner
CellDesigner is a modeling tool of biochemical networks with graphical user interface. It is designed to be SBW (Systems Biology Workbench) compliant, and support SBML (Systems Biology Markup Language) format.

Reactome
Reactome is a curated database of biological processes in humans. It covers biological pathways ranging from the basic processes of metabolism to high-level processes such as hormonal signalling. All the information in Reactome is backed up by either a literature citation or an electronic inference based on sequence similarity.

STKE - Signal Transduction Knowledge Environment
The STKE Connections Map database contains information on signaling components and their relations provided by leading authorities in the field. The database helps organize information and provides previously unavailable information such as short lists of selected key references, and the authorities' evaluations of the strength of existing evidence for relations in the database. The Connections Maps themselves are dynamically generated to instantly reflect new information provided by the authorities.

KEGG - Kyoto Encyclopedia of Genes and Genomes
KEGG is a suite of databases and associated software, integrating our current knowledge on molecular interaction networks in biological processes (PATHWAY database), the information about the universe of genes and proteins (GENES/SSDB/KO databases), and the information about the universe of chemical compounds and reactions (COMPOUND/GLYCAN/REACTION databases).

Systems Biology Institute
The Systems Biology Institute aims to provide information and tools needed to understand systems biology.