BMI1 and breast cancer: Bmi-1 expression was low in p16-negative immortalized 76N-TERT and MCF-10A cells [13,47] and moderate in 76R-30 cells, whereas it was abundant in all breast cancer cell lines analyzed, including SK-BR-3, ZR-75-30, BCAP-37 and MDA-MB-435S (Figure 4A).