Glyceollins enhance the NGF effect on PC12-ER differentiation. PC12-ER transfected with ERα and PC12-Cont transfected with empty plasmid (cartridge) cells were treated for 72 h with 5 ng of nerve growth factor (NGF) associated with solvent (black), E2 10-9 M (blue), various concentrations of glyceollin I (GI, gray) or glyceollin II (GII, red), or a mixture (1:1) of both GI and GII (green). PC12 cells were then photographed to determine the percentage of cells bearing neurites. The results are expressed as the percentage of cells bearing neurites in the presence of NGF + E2. The results are the mean of at least three independent experiments ± SEM. ** p-value < 0.01 and *** p-value < 0.001, with one-way ANOVA and Bonferroni’s post hoc test used to compare the control cells (NGF + solvent) with the other treatments. ### p-value < 0.001, with one-way ANOVA and Bonferroni’s post hoc test used to compare the NGF + E2-treated cells with the other treatments.