A truncated dominant negative form of the Jun transcription factor is expressed by this transgene. Transcription is directed by a tetracycline-responsive promoter element (TRE). When bred with another transgenic mouse expressing tetracycline-controlled transactivator protein (tTA) to create a bitransgenic animal, Fosb expression can be negatively regulated with the tetracycline analog, doxycycline. (J:83308)