G1 compartmentalization and cell fate coordination.

Pauklin and Vallier show that, whereas early G1 is permissive for TGF-β-dependent endoderm differentiation, cyclin D restricts the activity of Smad2/3 in late G1, resulting in a switch from endoderm to neuroectoderm potential in pluripotent stem cells. These findings provide insight into how signaling, the cell cycle, and lineage specification are coordinated.