Nerve growth factor activates a Ras-dependent protein kinase that stimulates c-fos transcription via phosphorylation of CREB

A mechanism by which the nerve growth factor (NGF) signal is transduced to the nucleus to induce gene expression has been characterized. An NGF-inducible, Ras-dependent protein kinase has been identified that catalyzes the phosphorylation of the cyclic AMP response element-binding protein (CREB) at Ser-133. Phosphorylation of Ser-133 stimulates the ability of CREB to activate transcription in NGF-treated cells. These findings suggest that CREB has a more widespread function than previously believed and functions in the nucleus as a general mediator of growth factor responses.