The Tango™ CMKLR1-bla U2OS cells contain the human Chemokine like receptor 1 (CMKLR1) 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 (bla) reporter gene under the control of a UAS response element.