The primary source of protein cleavage information is the published literature. Search profiles have been developed for use at PubMed (25) and Scopus (http://info.scopus.com/). These are updated regularly and currently include $500 names that are known to be used for peptidases. These retrieve a set of $250 potentially interesting abstracts each week. There is much redundancy, in that a single article may be retrieved by several search terms. Once a nonredundant list of articles has been obtained, the abstracts are reviewed to select the subset that is to be included in MEROPS. In a typical week, 50-60 references come through this filter. Keywords, including the MEROPS identifiers for the relevant peptidases, are manually attached to each and these determine which pages in MEROPS the reference will appear on. If from the abstract it is clear that the paper contains substrate-cleavage data these are entered immediately into the MEROPS collection. Periodically, the bibliography in MEROPS for a peptidase is reviewed to find substrate cleavages with a preference for peptidases without any substrates in the MEROPS collection.