Molecular biology of vertebrate learning: is c-fos a new beginning?

An elevated expression of c-fos nuclear protooncogene (immediate early gene) has been shown repeatedly to correlate with long-term neuronal responses. This paper reviews recent data suggesting that neuronal plasticity, including learning and memory formation, may involve c-fos expression as well. On the basis of biological functions of the Fos protein, well known to be a component of a transcription factor, AP-1, (activator protein 1) a hypothesis suggesting a role of transcription factors in the integration of information during learning processes is proposed.