The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP4487_r102376 http://rdf.wikipathways.org/Pathway/WP4487_r102376/DataNode/ab6da (MRP-transporter)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier