UV-induced downregulation of the CDC25B protein in human cells.

The CDC25B phosphatase regulates the activation of CDK1-Cyclin B at the onset of mitosis, being a key target of the checkpoint pathways activated by cellular stress and DNA damage. Previous work has reported that checkpoint activation induces the sequestration of CDC25B in the cytoplasm. Here we show that in response to UV irradiation, the levels of CDC25B protein can be downregulated independently of classical checkpoints pathways such as p53, ATM/ATR and p38 MAPK. We also show that translational repression mediated by eIF2alpha phosphorylation regulates CDC25B expression levels. Taken together, our results illustrate a new mechanism of CDC25B regulation in response to stress. Copyright 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.