FIGURE 2.

Activation of ERK1/2 promotes the translation of Ccnb1 mRNA and induces meiotic maturation. (A) Western blot analysis results revealing the ERK1/2 phosphorylation and CPEB1 levels at the appointed time points behind meiotic recovery. For each set of data, 100 oocytes were gathered and loaded. DDB1 was used for a control. (B) An illustration of microinjection and treatments to oocytes in (C–F). (C) Western blot analysis results revealing contents of indicated proteins in oocytes microinjected with mRNAs encoding MOS or constitutively active MEK (MEK1^S218D;S222D). One hundred oocytes were gathered and loaded in each lane. Numbers under blot bands indicate the intensity of each band. (D–F) Representative images (D), GVBD and PB1 emission (PBE) rates (E), and (F) immunofluorescence staining results of α-tubulin of oocytes in (C). DDB1 was used for a control. Numbers under blot bands indicate the intensity of each band. The accurate number of oocytes analyzed is labeled (n). Data were analyzed by mean ± SEM: **P < 0.05. Dashed lines indicate the oocyte outline. Scale bar: 100 μm. (G) An illustration of microinjection and treatments to oocytes in (H,I). (H) GVBD and PBE rates in oocytes that overexpressed MOS or MEK1^S218D;S222D by microinjection and further cultured in medium containing roscovitine (100 μM) for 24 h. The number of oocytes analyzed is labeled (n). Data were analyzed by mean ± SEM: *P < 0.05, **P < 0.01. n.s. indicates non-significant. (I) Western blot analysis results showing levels of indicated proteins in (G). For each set of data, 70 oocytes were gathered and loaded. DDB1 was used for a control. Numbers under blot bands indicate the intensity of each band.