Figure 3.

Effects of overexpressing XPR-1 in oocytes. (A) Sensitivity to progesterone. Oocytes were injected with H₂O (□) or 1 ng of XPR-1 mRNA (■), incubated overnight, and then stimulated with progesterone at indicated concentrations. Cells were scored for GVBD after 16 h. Ten oocytes from the same unprimed frog were tested at each concentration of hormone, because the EC₅₀ varied significantly from frog to frog. The relative increase in sensitivity to progesterone was similar in three different experiments. (B) Kinetics of GVBD. Groups of 40 oocytes from unprimed females were injected with H₂O (□) or 1 ng of XPR-1 mRNA (●), incubated overnight, and then stimulated with 10 μM progesterone. GVBD was scored at indicated times. Similar results were seen in four separate experiments.