Gene and Protein Description

Estrogen receptor 1 (ESR1; also known as ER) is a gene that encodes an estrogen receptor protein, estrogen receptor α (ERα). ESR1 is located on chromosome 6 (Gosden et al. 1986). Estrogen receptor β (ERβ) is a second estrogen receptor that plays a separate role in cancer biology and is encoded by a different gene (Thomas and Gustafsson 2011). The symbol ER generally refers to ERα. The protein functions in hormone binding. Estrogen receptors are important for sexual development and reproductive function. Missense mutations, nonsense mutations, silent mutations, frameshift deletions, and in-frame deletions are observed in cancers such as endometrial cancer, intestinal cancer, and stomach cancer.

Steroid Signaling Pathway

ER is a member of the steroid hormone signaling pathway, a cell signaling pathway that functions in transcriptional activation and gene expression. The pathway includes, but is not limited to, the following proteins: androgen receptor (AR), estrogen receptor 1 (ESR1), progesterone receptor (PGR), LRP1B, and TSHR. The steroid hormone signaling pathway may be activated by steroid hormones, such as estrogen and progesterone, which bind to a steroid binding protein.

Estrogen is a steroid hormone that controls cellular processes such as cell division, growth, differentiation, and proliferation. Estrogen is converted from androgen precursors by the aromatase enzyme. Aromatase converts androgens to estrogens. Estrogen acts as a ligand and binds to the estrogen receptor (ER), which results in changes in gene expression and the activation of signaling pathways that regulate cell growth processes, such as the cell cycle control signaling pathway.

Oncogenic Alterations in ESR1

ER Expression

ESR1 Mutations

Related Pathways

Contributors: Justin M. Balko, Pharm. D., Ph.D., Ingrid A. Mayer, M.D., M.S.C.I., Mia Levy, M.D., Ph.D., Carlos L. Arteaga, M.D.

Suggested Citation: Balko, J.M., Mayer, I.A., Levy, M., Arteaga, C.L. 2017. ER (ESR1). My Cancer Genome (Updated February 2017)

Modified: February 16, 2017

Disclaimer: The information presented at is compiled from sources believed to be reliable. Extensive efforts have been made to make this information as accurate and as up-to-date as possible. However, the accuracy and completeness of this information cannot be guaranteed. Despite our best efforts, this information may contain typographical errors and omissions. The contents are to be used only as a guide, and health care providers should employ sound clinical judgment in interpreting this information for individual patient care.