ESR1 and breast cancer: A functional study investigated the effects of spermine on estrogen receptor ER DNA-binding (ER-ERE complex), ER ligand-binding (estradiol), ER structure (circular dichroism and sucrose gradient sedimentation) and the capacity of ER to transactivate ERE-tk-CAT reporter in ER-positive MCF-7 and ER-negative MDA-453 breast cancer cell lines had been performed [44].