ESR1 and breast cancer: SLC6A14 has been suggested as a potential target for several solid tumors, including pancreatic, cervical, and colon cancers.[60] The high SLC6A14 level was also significantly correlated with poor post‐progress survival of breast cancer in a Kaplan‐Meier analysis.[61] Our study revealed the promoting effects of DEHP‐activated ERα on SLC6A14 upregulation and cancer stemness.