Effect of PD98059 on morphology, proliferation rates, pyknotic rates and steroidogenesis of GC cultured on LN. GC from small (a, c) and large (b, d, e, f, g, h) follicles were cultured for 144 h on LN in the presence or absence (control) of PD98059 at different concentrations (between 1 and 30 μM) in culture medium, and with or without anti-α6 IgG (0.5 μg/ml). (a, b): percentages of round cells at 48 h of culture; *** : p < 0.001, with anti-α6 IgG vs. control and PD98059-treated cells (30 μM). (c, d): proliferation rates and pyknotic rates of GC at 48 h of culture; empty bars: control; solid bars: with anti-α6 IgG in culture medium; in each graph, different letters indicate significant differences (p < 0.05); ** : p < 0.01, with vs. without anti-α6 IgG. (e, f): estradiol and progesterone secretions between 96 h and 144 h of culture; solid bars: with anti-α6 IgG in culture medium; data are expressed as percentages of control (100%, empty bars); in each graph, different letters indicate significant differences (p < 0.05) ; *** : p < 0.001 compared to control. (g, h): expression of P450scc (g) and 3βHSD (h) enzymes in GC at 144 h of culture, in control or in the presence of anti-α6 IgG or PD98059 (30 μM) in culture medium; results show representative western immunoblotting experiments performed on 5 μg of GC extracts; data correspond to quantification of autoradiograms in arbitrary units (control mean = 100); * : p < 0.05, ** : p < 0.01, treated vs. control. Data of the Figure represent mean ± SEM of 4 to 8 independent experiments.