Figure 1
From: Estrogen regulation of mammary gland development and breast cancer: amphiregulin takes center stage
Mammary stem cells and the estrogen receptor (ER). ER-negative stem cells may asymmetrically divide to self-renew and to give rise to undifferentiated ER-positive progenitor cells. In response to estrogens, ER-positive progenitors secrete paracrine factors, such as amphiregulin (AREG) that can influence the proliferation and/or differentiation of ER-negative stem cells. E2, estradiol.