A tale of two clocks: phosphorylation of NICD by CDKs links cell cycle and segmentation clock.

The Notch signaling pathway is tightly controlled via post-transcriptional regulatory mechanisms that promote or terminate pathway activity. In this issue, Carrieri et al [1] show that phosphorylation of the Notch intracellular domain (NICD) by cyclin-dependent kinases (CDKs) suppresses Notch activity by promoting NICD turnover. These findings link Notch pathway activity to the cell cycle, and the authors propose connections between this regulation and the segmentation clock that times embryonic somitogenesis.