Secondly, in the study on signaling pathways, 10−8 M estrogen treatment for 1 h again increased Arc protein (Fig. 3A–E) and mRNA (Fig. 3F) expression in SH-SY5Y cells. However, pre-incubation of cells with 200 nM ICI182,780, 200 nM Wortmannin, or 1 μM U0126 completely abolished the estrogen-induced Arc expression. Pre-incubation with either 1 μM Y27632 or 200 nM GFX had no effect on reducing the estrogen-induced Arc expression. These data indicate that estrogen acts through ER-, PI-3K-, and MAPK-dependent pathways in order to enhance Arc transcription and translation.