Tango™ GPR39-bla U2OS cells contain the orphan human G-protein Coupled Receptor 39 (GPR39) 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™ GPR39-bla U2OS cells have been functionally validated for a receptor specific response to FBS. In addition, Tango™ GPR39-bla U2OS cells have been tested for assay performance under variable conditions.