SGK directly phosphorylates Cdc25 and Myt1. (A) SGK, but not Akt, is required for Cdk-independent phosphorylation of Cdc25 and Myt1 upon 1-MeAde stimulation. Oocytes were injected with the indicated antibodies, treated with 1-MeAde in the presence of roscovitine, and then analyzed by immunoblotting using a normal or Phos-tag–containing SDS-PAGE gel. Open arrowheads indicate position of active SGK. (B) His-tagged recombinant WT sfCdc25 or the S188A mutant was incubated with or without GST-tagged active hSGK3 in the presence of ATP and MgCl2. Thereafter, immunoblotting was performed. (C) GST-tagged recombinant kinase-dead (KD) or the S75A mutant of sfMyt1 was phosphorylated by hSGK3 as described in B. Asterisks indicate minor fragments of recombinant Myt1. The data in A–C are representative of two independent experiments. Full blots for A–C are presented in Fig. S7.
