Blockage of daidzein-induced neuritogensis by kinase inhibitors of Src and MEK, but not by ER antagonists. (A) DRG neuronal cultures were treated for 24 h with (a) DMSO, or (b) 30 μM daidzein. Inhibitor assay was conducted by pretreatment of DRG neuronal cultures for 30 min with (c) ER antagonist ICI182780 at 1 μM, (d) GPR-30 antagonist G15 at 100 nM, (e) Src kinase inhibitor PP2 at 10 μM, or (f) MEK inhibitor U0126 at 10 μM, followed by 30 μM daidzein for 24 h. The neurons were fixed and immunostained for NF-L. Scale Bar = 30 μm. (B) Analysis of total neurite length and tip number revealed that PP2 and U0126 significantly blocked the neuritogenesis induced by daidzein. **, p ≤ 0.01 vs DMSO group; ##, p ≤ 0.01 vs daidzein group. N = 10.