ESR1 and breast cancer: SVCT2 expression was then evaluated in the hTERT-immortalized, normal human breast epithelial line (BPE3) and in four breast cancer lines: estrogen receptor positive (ER+)/progesterone receptor positive (PR+) luminal MCF7, ER+/PR− luminal ZR751, and triple negative (ER−/PR−/HER2−) basal lines, MDA-MB-231 and BT549.