Signal transduction from the cell surface to the nucleus through the phosphorylation of transcription factors.

The activation of several transcription factors in response to extracellular stimuli is fairly well understood. In all cases, activation is mediated through phosphorylation by signal responsive protein kinases. The specificity of transcription factor phosphorylation is likely to be ensured by physical interactions between the protein kinases and their substrates. Distinct biological responses are likely to be mediated through activation of different constellations of protein kinases, resulting in phosphorylation of different transcription factors.