The MetaCyc database of metabolic pathways and enzymes and the BioCyc collection of Pathway/Genome Databases. - Ron Caspi; Tomer Altman; Richard Billington; Kate Dreher; Hartmut Foerster; Carol A. Fulcher; Timothy A. Holland; Ingrid M. Keseler; Anamika Kothari; Aya Kubo; Markus Krummenacker; Mario Latendresse; et al. (Nucleic Acids Res., 2014)