FIG. 13.

Model of Wee1 regulation by the NES/RXL1 bifunctional regulatory element. Cyclin A/Cdk complexes are freed from RXL-containing S-phase substrates by accumulation of these Cdk complexes and S-phase progression. The Cdk complexes bind RXL1, which directs phosphorylation of T239 and possibly other sites [(S/T)X] that foster nuclear export of Wee1. T239 phosphorylation abrogates stimulation of kinase activity by the Wee box. Crm1 binds the Wee1 NES and directs nuclear export. cycA, cyclin A.