ESR1 and neoplasm: These changes are accompanied by a reduction in tumor size and the expression of ER-α, HIF-α, VEGF, TNF-α, CD31 (a marker of angiogenesis), and Ki67 (a marker of proliferation) in tumor tissue, as well as in the serum levels of estradiol (E2), and an increase in the mRNA levels of PDCD-4 (a tumor suppressor and target of miR-21).