Tango™ GPR1-bla U2OS cells contain the human G protein-coupled receptor 1 (GPR1) linked to a TEV protease site and a Gal4-VP16 transcription factor stably integrated into the Tango™ GPCR-bla U2OS parental cell line. This parental cell line stably expresses a beta-arrestin⁄TEV protease fusion protein and the beta-lactamase reporter gene under the control of a UAS response element. The Tango™ GPR1-bla U2OS cells have been functionally validated for Z’ factor and EC50 concentrations of Chemerin (Figure 1). In addition, Tango™ GPR1-bla U2OS cells have been tested for assay performance under variable conditions.