We have selected to study two representative miRNAs from each family: miR-29b (a potent inhibitor of breast tumor metastasis [34]) and miR-29c (associated with a significantly reduced risk of dying from breast cancer [41]), miR-30b and miR-30d (both significantly down-regulated in ER-negative and progesterone receptor (PR)-negative breast tumors [42]), and miR-200b and miR-200c (both representing key negative regulators of EMT and anoikis resistance [30-32]). The gene discussed is ESR1; the disease is breast neoplasm.