The response of a chimeric cellular model to a hormone has to be more specific, more sensitive, more easily measurable and quantifiable than the natural response. Hence, it can be used either in fundamental and applied studies, for example to analyse hormonal interactions, or to screen new hormone molecules. In the field of steroid hormones, we took benefit from the advantages of the firefly luciferase as receptor gene (simplicity and rapidity of the measurement, high sensitivity, handiness ...) to construct such chimaeric models. Such cell lines were obtained by developing another original use of this reporter gene based on an easy detection of the luciferase activity in intact living cells and using a photon counting camera. This was successfully adapted to obtain and to detect stable transfected cells.