Upregulation and activation of δ-opioid receptors promotes the progression of human breast cancer

δ‑opioid receptor (DOR) belongs to the family of G protein‑coupled receptors (GPCRs). Numerous studies have shown that DOR is widely distributed in human peripheral tissues and is closely related to the development and progression of certain malignant tumours. However, there is controversy in the literature regarding whether DOR has an impact on the development and progression of human breast cancer. The present study comprehensively elaborates...