In comparison with the control group, the ulinastatin group displayed decreased viability of breast cancer cells, a decreased positive rate of 5-ethynyl-2′-deoxyuridine (EdU) staining, an increased positive rate of Hoechst 33258 staining, and reduced mRNA and protein levels of ERK and FOXO3 in breast cancer cells. The gene discussed is FOXO3; the disease is breast cancer.