Table 1 shows the clinical and pathologic characteristics of breast cancer patients in association with MAD2L1 and BUB1 expression. Patients with PR negative, ER negative, and high grade tumors had higher expression of MAD2L1 and BUB1 compared to those with PR positive, ER positive, and low grade tumors, respectively. Patient age, disease stage and lymph node involvement were not associated with MAD2L1 or BUB1 expression. This evidence concerns the gene ESR1 and breast cancer.