**GPER Mediates Estrogen-Induced Signaling and Proliferation in Human Breast Epithelial Cells and Normal and Malignant Breast Tissue**
17-Estradiol (E2), through receptor binding and activation, is essential for mammary gland development. It stimulates epithelial proliferation, driving ductal elongation and morphogenesis during puberty. Beyond its developmental role, E2 promotes…