雌激素受体是细胞核受体之一，在多组织中存在多种表达形式，参与雌激素调控基因特异性表达的生理过程。雌激素受体阳性乳腺癌占比高达所有乳腺癌亚型的 70%。雌激素受体α是雌激素受体两大主要的亚型之一，促进了乳腺癌的发生和雌激素受体阳性乳腺癌的发展。探究雌激素受体α互作蛋白的种类、结构、功能和作用方式，对于深入理解雌激素受体α与互作蛋白的效应，包括受体自身的合成、降解、定位、修饰、信号通路激活等机制，与受体对互作蛋白的生物学功能调控机制，具有重要的参考意义与应用价值。
本研究通过 CRISPR/Cas9 系统，在人类雌激素受体阳性乳腺癌细胞系 MCF7内源编码 ERα的基因 ESR1 N 端敲入标签序列，构建不同 tag-ESR1 MCF7 细胞系。这些细胞系可进一步应用于免疫沉淀-质谱联用、亚细胞共定位、免疫共沉淀等技术，为研究内源雌激素受体α互作蛋白提供了基础的细胞实验材料。

Estrogen receptor is one of the nuclear receptors. It has multiple expression forms in different tissues, which participates in the physiological process of estrogen-regulated gene-specific expression. Estrogen receptor-positive breastcancer accounts for up to 70% of all breast cancer subtypes. Estrogen receptor α, one of the two main subtypes of estrogen receptors, promotes the occurrence of breast cancer and the development of estrogen receptor-positive breast cancer. Exploring the type, structure, function and mode of action of estrogen receptor α -interacting proteins gives an insight into the effects of estrogen receptor α and interacting proteins, including the mechanism of receptor, itself, synthesis, degradation, localization, modification, signal pathways activation and regulation mechanism of receptor-interacting proteins. The study is significant and has application value . In this study, Using the CRISPR/Cas9 system, a tag sequence is knocked into the N-terminal of the endogenous gene ESR1, which encodes estrogen receptor α, in the human estrogen receptor-positive breast cancer cell line MCF7 to construct different tag-ESR1 MCF7 cell lines. These cell lines can be further applied to techniques such as Immunoprecipitation-Mass Spectrometry,  subcellular co-localization, and Co-Immunoprecipitation, providing basic cell experimental materials for the study of endogenous estrogen receptor α -interacting proteins.