Figure 1.

KEGG consists of eighteen original databases in four categories. The health information category, called KEGG MEDICUS, is supplemented with two outside databases of drug labels: Japanese drug labels obtained from JAPIC (http://www.japic.or.jp) and FDA drug labels linked to the DailyMed database (https://dailymed.nlm.nih.gov). The identifier of each entry in the KEGG database generally takes the form of a prefix followed by a five-digit number and is called, for example, map number, M number and K number for the PATHWAY, MODULE and KO databases, respectively.