Figure 4.

Effects of ICI172,780 and 17α-estradiol on cAMP production in MCF-7 cells enriched for membrane estrogen receptor-α (mER^high) cells. (a) ICI172,780 inhibited 17β-estradiol (E₂)-induced cAMP production. Both simultaneous application of 1 μmol/l ICI172,780 and 1 pmol/l E₂ (open circle) or 30 min pretreatment with ICI172,780 (open square) was tested. (b) 17α-Estradiol was applied at a 10 nmol/l concentration and the time dependent cAMP production was followed. Closed circles represent E₂ induced cAMP production, redrawn for comparison from Fig. 2a.