To divide the breast cancer samples into different subtypes, the following surface markers were used: luminal A (ER+ and/or PR+, HER2−), luminal B (ER+ and/or PR+, HER2+), basal-like (ER-, PR-, HER2-), HER2-enriched (ER-, PR-, HER2+) [22]. Here, ESR1 is linked to breast cancer.