To address whether adipocytes play a role in promoting breast cancer resistance to DOX, a panel of estrogen receptor (ER)-positive (T47D), HER2-positive (MDA-MB453, BT-474), and triple-negative (TN) (MDA-MB436, MDA-MB231, M-Wnt, and E0771) human and murine breast cancer cell lines was cocultivated (or not) with adipocytes. The gene discussed is ESR1; the disease is breast carcinoma.