Oscillatory dynamics of the extracellular signal-regulated kinase pathway.

The extracellular signal-regulated kinase (ERK) pathway is a central signaling pathway in development and disease and is regulated by multiple negative and positive feedback loops. Recent studies have shown negative feedback from ERK to upstream regulators can give rise to biochemical oscillations with a periodicity of between 15 and 30min. Feedback due to the stimulated transcription of negative regulators of the ERK pathway can also give rise to transcriptional oscillations with a periodicity of one to two hours. The biological significance of these oscillations is not clear, but recent evidence suggests that transcriptional oscillations participate in developmental processes, such as somite formation. Biochemical oscillations are more enigmatic, but could provide a mechanism for encoding different types of inputs into a common signaling pathway.