ESR1 and breast cancer: The expression of cell surface GRP78 and its downstream transcription factor, CREB3L1, was induced by the addition of doxorubicin and paclitaxel to cultures of ER positive MCF7 (n = 11), HER2-neu positive BT474 (n = 4), and triple-negative MDAMB231 (n = 8) and MDAMB468 (n = 7) breast cancer cell lines.