The luminal breast cancer cell line MCF-7 was transfected with miRNA mimics (20 nM) and assayed for cell proliferation (Ki67) (a); apoptosis (cleaved PARP (cPARP)) (b); estrogen receptor (ER) levels (c); phosphorylated AKT (p-AKT) levels (d); cell viability (e), 72 hours after transfection. The gene discussed is ESR1; the disease is breast cancer.