The Semantic Systems Biology group at NTNU has been a regular user of BioPortal for many years. BioPortal has been very helpful as a resource for identifying and downloading ontologies most suitable for our projects.  In a complementary way, we have also used BioPortal for disseminating application ontologies developed in our group: the Cell Cycle Ontology (CCO), the Gene Expression Ontology (GeXO), the Regulation of Gene Expression Ontology (ReXO) and the Regulation of Transcription Ontology (ReTO). We are honestly grateful to all the members of the BioPortal team for the continuous support they provide to the research community.