The following DataNodes have no identifier: 2
http://classic.wikipathways.org/instance/WP1004_r115956 http://rdf.wikipathways.org/Pathway/WP1004_r115956/DataNode/ab2ca (GAB2)
http://classic.wikipathways.org/instance/WP1004_r115956 http://rdf.wikipathways.org/Pathway/WP1004_r115956/DataNode/a6aea (PIK3R2)
More details at https://www.wikipathways.org/WikiPathwaysCurator/DataNodesTests/dataNodesWithoutIdentifier