ESR1 and breast cancer: Considering that ER isoforms alpha and beta are involved in BC progression and glycolysis, to examine whether this biological process could occur through H19 and hTERT and with the aim of exploring whether ATRA could regulate this signaling pathway, we transfected treated or untreated MDA-MB-231 cells with ER(α) or ER(β) expression plasmids for 48 h.