ESR1 and breast cancer: To assess if ICI 182,780 (fulvestrant), a selective antagonist of estrogen receptors alpha and beta (ERα/ERβ), and G-1, a selective G-protein-coupled estrogen receptor (GPER) agonist, can potentially induce autophagy in breast cancer cell lines MCF-7 and SKBr3, and if G-1 can affect cell viability.