Figure 5.

Effects of E₂, P₄, and their combinations on cell proliferation and signaling in primary mouse pituitary cells and rat somatomammotroph GH3 cells. (A) Expression of Ccnd1 mRNA in primary pituitary cells isolated from 5-month-old TG mice and stimulated for 24 h as indicated. The results are mean±s.e.m. of five individual experiments. Different letters indicate significant differences (P<0.05) between the treatment groups. (B) Effects of 48 h P₄ stimulation on GH3 cell proliferation when co-treated with E₂ and/or mifepristone (Mf). The mean cell number in controls was taken as 100%, and those of the other treatments were related to this figure (mean±s.e.m. of 5–6 independent experiments). *P<0.05, **P<0.01 versus basal plus 100 pM E₂; ^†P<0.05, ^††P<0.01 vs 0.1 nM P₄; ^‡P<0.05, ^‡‡P<0.01 vs 1 nM P₄; ^§P<0.01 vs 0.1 and 1 nM P₄+1000 pM E₂+10 μM Mf.