is a potential progenitor–like biomarker for breast cancer. Protein expression levels of RRM2 and other markers were determined by immunohistochemical (IHC) staining. The representative images are: A) multiple staining with CD44/CD24, ki-67 and RRM2, B) CD44+/CD24+ sample negative for ki-67 and RRM2 in the left panel, CD44+/CD24 -/low positive for ki-67(+) and RRM2 (+) in right panel. RRM2 is correlated with CD44+/CD24-/low and ki-67, as shown in (C) and (D), respectively. (E)
RRM2 expression was significantly associated with poor differentiation. (F)
RRM2 was highly expressed in Luminal B, HER2-positive and TNBC molecular subtypes.