To evaluate whether E2F8 correlates clinically with breast cancer progression, the expression of E2F8 was examined by immunohistochemistry (IHC) in 187 paraffin-embedded, archived breast cancer tissues, including 33 cases of clinical stage I (17.6%), 95 cases of stage II (50.8%), 51 cases of stage III (27.3%) and 8 cases of stage IV breast cancers (4.3%) (Supplementary Table 1). The gene discussed is E2F8; the disease is breast cancer.