This result contrasts with the observed alteration in nucleo-cytoplasmic shuttling of mouse ERα in transfected COS-1 cells [32], but is in agreement with differential extraction experiments in MCF-7 cells [24, 40], and with localization of transfected GFP-tagged ERα in various BC cell lines treated with ICI182,780 [41, 42]. Here, ESR1 is linked to breast cancer.