When the analysis was restricted to the luminal ER+ tumours, high BMI1 expression was associated with low expression of ALDH1A1 (P = 0.025), ALDH1A3 (P = 0.026), CD133 (P = 0.038), CD44 (P = 0.0001), CD24 (P = 0.004) and SOX10 (0.0006) (Supplementary Table 4b). Here, CD44 is linked to neoplasm.