In this thesis, several orthosteric and allosteric agonists are presented for the newly discovered hydroxy-carboxylic acid (HCA) receptor 2, and their in vivo activity or in vitro structure... Show moreIn this thesis, several orthosteric and allosteric agonists are presented for the newly discovered hydroxy-carboxylic acid (HCA) receptor 2, and their in vivo activity or in vitro structure-activity relationships are described. The literature on HCA receptors was also thoroughly reviewed, providing some insight into the future of this receptor family as drug targets. The anti-cancer drug N6-(2-isopentenyl)adenosine (IPA) was shown to be a specific ligand for the adenosine A3 receptor, and its antiproliferative effect seems to be mediated by this receptor at low concentrations. A ligand discovery screen for orphan receptor GPR88 was performed, in which over 4000 compounds were tested. Show less