Fig. 3.
Gwl activation and phosphorylation of ARPP19 at S67 rely on Cdk1 activation. (A) Prophase-arrested oocytes (Pro) were injected or not with p21Cip1 (Cip1), then injected or not with 77.5 ng of WT-GST-ARPP, and where indicated, treated with progesterone (Pg). Oocytes were collected at GVBD and GST-ARPP was pulled down. Supernatants after the pull down were analyzed by western blot for Gwl, Cyclin B1, Cyclin B2, phosphorylated MAPK (pMAPK), Y15-phosphorylated Cdk1 (pY15-Cdk1) and phosphorylated Cdk1 substrates (pCdk substrates). (B) Western blot analysis of GST pull-down fractions corresponding to experiment (A) for S67-phosphorylated WT-GST-ARPP (pS67-GST-ARPP), PP2A-A, PP2A-C, PP2A-B55δ.