Cdc25b phosphatase is required for resumption of meiosis during oocyte maturation

In a wide variety of animal species, oocyte maturation is arrested temporarily at prophase of meiosis I (ref. 1). Resumption of meiosis requires activation of cyclin-dependent kinase-1 (CDK1, p34cdc2), one component of maturation-promoting factor (MPF) 2,3 . The dual specificity phosphatases Cdc25a, Cdc25b and Cdc25c are activators of cyclin-dependent kinases4‐8; consequently, they are postulated to regulate cell-cycle progression in meiosis and mitosis as well as the DNA-damage response 9‐12 . We generated Cdc25b-deficient (Cdc25b ‐/‐ ) mice