Fig. 2. Expression of the regulators of Cdc2 activation during oogenesis. (A) Prophase oocytes at stage IV (750-800 µm), stage V (900-11,000 µm) and stage VI (1200 µm) were incubated or not in the presence of progesterone and collected 18 hours afterwards. Oocyte extracts were western blotted with antibodies against cyclin B2, the active phosphorylated form of MAPK (P-MAPK), Mos, MAPK, the Thr161-phosphorylated form of Cdc2 (P-Thr161-Cdc2), Plkk1 and Myt1. (B) RT-PCR analysis of Plx1 transcripts. Total RNA of oocytes at various stages was subjected to RT-PCR analysis using Plx1 or Myt1 oligonucleotides as primers. Myt1 was used as the loading control. Without reverse transcription (Plx1 RT^-), no amplification products were detectable using Plx1 primers.