Fos/EGFP transgenic mice express a fusion gene consisting of the murine FBJ osteosarcoma oncogene (Fos) and enhanced green fluorescence protein (EGFP). Hemizygous Fos/EGFP mice are viable, fertile, and normal in size. Fos is a member of the activator protein-1 family of transcription factors and serves as a marker for neural activity. At basal state, Fos is expressed at low levels in the cerebellum, olfactory bulb, hippocampus, and neocortex. Fos expression is induced by a wide array of stimuli, including seizure, cortical injury, dehydration, and pain. In these mice, the Fos/EGFP fusion protein is expressed in recently activated neurons. These mice may be useful for visualizing Fos-expression in stimulated neurons, and for studying changes in neuron excitability and synaptic efficacy.
