ESR1 and breast cancer: Human breast cancer cells MCF7 (luminal; estrogen receptor+ (ER+), progesterone receptor+ (PR+)), MDA-MB 231 (basal; triple-negative breast cancer, (TNBC)), T47D (luminal; ER+, PR+), MDA-MB468 (basal; TNBC), ZR-75-1 (luminal; ER+, PR+) and SK-BR3 (luminal; Her2+) were stably transduced with retroviral vectors expressing LIF, and the levels of glucose uptake were examined by measuring the uptake of 3H-2-deoxyglucose (3H-2-DG) as we previously described [21].