ESR1 and triple-negative breast carcinoma: In ERα-positive (30) and triple-negative breast cancer (TNBC) cells (MDA-MB-231) (31), BPA activates signal transduction pathways [i.e., extracellular signal-regulated kinase 1/2 (ERK1/2)] involved in proliferation via G-protein coupled estrogen receptor (GPER) and epidermal growth factor receptor (EGFR).