Studies on the regulation of subcellular localization ER_ by estrogen in SH-SY5Y cells show that, in the absence of estrogen (control), ER_ localized in cytoplasmic and membranous regions of SH-SY5Y cells (arrowhead in Fig. 2). After estrogen treatment, membranous and cytoplasmic ER_ gradually decreased, but the nuclear ER_ increased progressively with the incubation time (0.5, 1 and 3 h).