The following DataNodes have no identifier: 1
http://classic.wikipathways.org/instance/WP4763_r108519 http://rdf.wikipathways.org/Pathway/WP4763_r108519/DataNode/b77f5 (Mitochondrial biogenesis)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier