The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP5055_r122621 http://rdf.wikipathways.org/Pathway/WP5055_r122621/DataNode/db8c1 (Activin)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier