MKI67 and breast cancer: Consistent with the fact that ER+ and PR+ BC are less likely to achieve pCR, they observed that the corresponding receptor coding genes (ESR1 for ER and PGR for PR) were overexpressed in RCB-II and RCB-III patients and not in pCR status or RCB-0/I (p = 0.00053 and 0.0061, respectively); on the other hand, the expression level of MKI67 was lower in RCB-III than in RCB-0/I and RCB-II (p = 0.0029).