Abstract: The present invention refers to the renin/prorenin receptor (RER) signal transduction pathway and, in particular, to the role of promyelocytic zinc finger protein (PLZF) and its downstream targets involved in this pathway, e.g. the p85? subunit of phosphatidylinositol-3 kinase (PI3K-p85?). In more detail, the present invention refers to a method for determination of RER activity, e.g. stimulation or inhibition of RER activity, using PLZF activity as a measurement from which RER activity is derived. For the determination of RER activity, use can be made of RER/PLZF protein interaction, PLZF translocation and/or PLZF recruitment. The present invention further refers to a use of said method for identifying RER ligands, e.g. pharmaceutically active agonists or antagonists, as well as for studying undesired side-effects of renin inhibitors.