To date, the proto-oncogene Bmi-1 has been reported to be up-regulated in a large number of neoplasias, namely in lymphomas [27], cerebral tumours [26], breast cancer [13] and other epithelial tumours [28,29] and to be an oncogene associated with poor prognosis in various tumours [12]. The gene discussed is BMI1; the disease is breast carcinoma.