The Cover

Immunofluorescent localization of the estrogen receptor alpha (ER, red) and the human epidermal growth factor receptor 2 (HER2, green) in HER2-overexpressing MCF-7 breast cancer cells. The majority of ER in MCF-7 cells is normally localized to the cell nucleus. In HER2 overexpressing cells, however, ER relocalizes from the cell nucleus (blue) to the cell cytoplasm and plasma membrane, where it colocalizes (yellow) with HER2.