1 4-AP decreased progesterone output by serum-supplemented granulosa cell cultures. A) Progesterone accumulation by 24 h GC cultures maintained in the basic culture media containing 10% FBS (Control) in the absence or presence of 4-AP (2 mM). B) Progesterone accumulation by 24 h GC cultures maintained in the basic culture media in the absence or presence of added FSH (200 ng/mL) and/or 4-AP (2 mM). Data are normalized to day 0 progesterone concentrations, and represent the mean ± SEM of either 33 culture wells from 6 GC harvests (panel A) or 17 culture wells from 4 GC harvests (panel B). Asterisks indicate P < 0.05 compared with GC cultured under similar conditions in the absence of 4-AP.