The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP5031_r122564 http://rdf.wikipathways.org/Pathway/WP5031_r122564/DataNode/a1250 (Proteolysis)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier