The development of a cell-based system that allows the integration of a gene of interest (GOI), such as a G protein-coupled receptor (GPCR), into a specific site on the genome, has made the generation of mammalian cell lines able to express such proteins easy and efficient. Flp-In™ stable cell lines are isogenic and hence protein expression is constant across a population of cells. A useful addition to the Flp-In™ system (Flp-In™ T-Rex™) allows this expression to be controlled by the addition of a small molecule inducer to the cell culture medium. Stable cell lines generated as described here can be used to great advantage in the study of receptor pharmacology signalling and oligomerisation.