Fig. 1.

Erk and EGFR signaling are necessary for LH-induced steroid production in preovulatory follicles. Preovulatory follicles from PMSG-primed female mice were preincubated with 0.01% DMSO, 20 μm U0126 (A and B), or 20 μm AG1478 (C and D) for 30 min. LH (0.2 mg/ml) was used to stimulate follicles for the indicated times in the presence of the indicated inhibitors or DMSO. Progesterone concentrations in the medium were measured by RIA (A and C), and cell lysates were collected at 2 h and analyzed by Western blot for phosphorylated and total Erk (P- and T-Erk) by Western blot (B and D). Experiments were repeated at least three times with similar results. Each bar represents the mean ± sem (n = 3). *, P < 0.05 by Student's t test relative to LH alone.