<p>Tamoxifen treatment in breast cancer patients is associated with increased risk of endometrial malignancies. Significantly, higher <i>AGR2</i> expression was found in endometrial cancers that developed in women previously treated with tamoxifen compared to those who had not been exposed to tamoxifen. An association of elevated <i>AGR2</i> level with myometrial invasion occurrence and invasion depth was also found. <i>In vitro</i> analyses identified a stimulatory effect of <i>AGR2</i> on cellular proliferation. Although adverse tamoxifen effects on endometrial cells remain elusive, our work identifies elevated <i>AGR2</i> as a candidate tamoxifen-dependent mechanism of action responsible for increased incidence of endometrial cancer.</p
