MIB1 and breast cancer: Defining breast cancer intrinsic subtypes by quantitative receptor expression showed 73.6% (n = 78) luminal A (ER + or PR + , HER2-, MIB1 < 14%), 17.9% (n = 19) luminal B (ER + or PR + , HER2 ± , MIB1 ≥ 14%), 0% HER2 driven and 2.8% (n = 3) basal-like (ER-/PR-/HER2-) cancers while 6 cases could not be defined because of missing data.