To profile the (phospho)proteomes of breast cancer-derived EVs, we isolated EVs secreted from nine different breast cancer cell lines; one low-grade luminal-type non-metastatic breast cancer cell line (MCF7), four triple negative (Hs578T, BT549, MDA-MB-231, LM2), and four HER2 positive/ER negative (HCC1954, HCC1419, JIMT1, SKBR3). The gene discussed is ESR1; the disease is breast cancer.