pathwaycommons.org/pc2/graph?source=http for L-citrulline, ChEBI ID:16349). The identifiers are unified to ChEBI for metabolites and HGNC-names for proteins, although the query itself can contain a mix of URIs from UniProt, NCBI Gene, and ChEBI IDs. The output does not provide information from which database the reaction information originates, nor a (potential) publication connected to a reaction. Even though the unification of several pathway databases creates a massive knowledgebase, information will get lost in this unification process, which should be taken into account when extending the DSMN, as well as the lack of provenance.