Angiotensin (Ang)-(1-7) has cardiovascular protective effects and is the opponent of the often detrimental Ang II within the renin-angiotensin system. The study aimed to identify a second messenger stimulated by Ang-(1-7) allowing confirmation as well as discovery of the heptapeptide's receptors. Ang-(1-7) elevates cAMP concentration in primary cells, such as endothelial or mesangial cells. Using cAMP as readout in receptor-transfected human embryonic kidney (HEK293) cells, the study provided pharmacological proof that Mas is a functional receptor for Ang-(1-7). Moreover, the authors identified the G-protein-coupled receptor MrgD as a second receptor for Ang-(1-7).