Among the proliferation-associated proteins (TOP2A, MCM2, and BUB1B) that we have studied immunohistochemically on a set of IDCs and validated as immunohistochemical biomarkers of malignancy in histologically normal breast tissues, TOP2A and BUB1B protein are also known targets of established chemotherapeutic approaches in breast cancer: anthracyclines and antimicrotubule therapies, respectively. The gene discussed is BUB1B; the disease is breast carcinoma.