EGF induces granulosa cell proliferation via the activation of the MAPK and PI3K/Akt pathways. KGN and SVOG cells were serum starved for 12 h and incubated in serum-free medium containing various concentrations of EGF and/or AG1478 for various periods of time. KGN cells (A) and SVOG cells (C) were left untreated (Control) or treated with increasing concentrations of EGF and/or AG1478 for 48 h. The viability was measured by the MTT assay. The data derived from at least three separate sets of experiments were standardized to the corresponding control, and the statistical results are presented in the column graphs. a, P < 0.05 compared with control; b, P < 0.05 compared with treatment with EGF 100 ng/mL alone. KGN cells (B) and SVOG cells (D) were treated with 100 ng/mL EGF for 5 min, 10 min, 30 min, 1 h, 3 h or were untreated (Control). The phosphorylation of ERK1/2 or Akt was determined by Western blotting with specific antibodies.