Is a protein found in high concentrations in the cytoplasm of breast, uterus, hypothalamus, and anterior hypophysis cells; ER levels are measured to determine a breast CA’s potential for response to hormonal manipulation.
A cellular protein that binds female sex steroid hormones. When estrogens attach to it, they stimulate cells to transcribe DNA and manufacture proteins, typically leading to cellular growth and proliferation.
A cellular surface protein that binds with the female hormone estrogen, initiating estrogenic responses, and found on breast cancer cells that express estrogen receptors (ER-positive).