Figure 1.

The circadian oscillator mechanisms from flies and mice: models depicting the regulatory interactions within the Drosophila and mouse feedback loops. Arrows indicate positive regulation and lines ending in bars denote negative regulation. Gene symbols are as described in the text. The 'P' on Per and mPer represents phosphorylation due to Dbt/CK1ε. The lightning bolt represents light acting on Drosophila Cry.