(A) At 5.5 dpc, implantation sites in Dedd^+/+ and Dedd^–/– uteri were immunostained for cyclin D3. Bottom panels show higher magnifications of the dotted area in the middle panels. Scale bars: 200 μm. Graph on the right: Cyclin D3–positive cells within an implantation site were counted and compared in at least 4 different sections, and the means are presented. Error bars indicate SEM. (B) Immunoblotting of Dedd^+/+ and Dedd^–/– uteri at 5.5 dpc for cyclin D3 and quantification of results. Three mice were analyzed. Error bars indicate SEM. (C) mRNA level for cyclin D3 in 5.5-dpc implantation sites. No significant decrease in mRNA level was detected in Dedd^–/– cells and tissues (n = 3 for each). (D) Protein degradation assay for cyclin D3. Uterine stromal cells at day 3 of in vitro decidualization were treated with cycloheximide (CHX; 50 μM) for the indicated periods in the presence or absence of proteasome inhibitor MG132 (10 μM). At each time point, cells were harvested, and the lysate was analyzed for cyclin D3 by immunoblotting. The amount of cyclin D3 protein at each time point was normalized to that of β-actin and is presented as relative level to that at pretreatment (0 minutes) in Dedd^+/+ or Dedd^–/– cells. Three independent experiments were performed, and representative blots are presented. Error bars indicate SEM. (E) In vitro decidualizing Dedd^–/– stromal cells were transfected with expression vector for FLAG–cyclin D3 at day 2. At day 5, cells were stained for FLAG and Hoechst; thereafter, the proportion of polynuclear cells among more than 100 FLAG-positive cells was evaluated microscopically. Average results from 4 independent sets of experiment are presented. Error bar indicate SEM. *P < 0.05, **P < 0.01, ***P < 0.001.