ESR1 and breast cancer: Indeed, the higher expressions of SLC6A14 (Figure S10A, Supporting Information) and SOX2 (Figure S10B, Supporting Information) in tumor tissues and younger age of diagnosis (Figure S10C, Supporting Information) were observed in patients with the ERα‐positive breast cancers, particularly in luminal B subtype, further substantiating the significance of the ERα/SLC6A14 axis in influencing cancer stem cell properties for the early onset of breast cancer in response to DEHP exposure.