In this study, the effect of genistein on the expression of miR-27a as a tumor suppressor, miR-151 as an oncogene, and genes involved in apoptosis and autophagy, including ATG12, Beclin1, Caspase 3, and Caspase 9, in EJ138 BC cells was investigated using real-time PCR. The gene discussed is CASP3; the disease is breast cancer.