Figure 1. RRM2 is upregulated in EOC cells and tumor specimens. (A) Expression of RRM2 protein in 3 individual isolations of normal human ovarian surface epithelial (HOSE) cells and the indicated human EOC cell lines by immunoblotting. β-actin was used as a loading control. (B) Immunohistochemical staining of RRM2 protein expression in normal ovary, normal fallopian tube, and human EOC tissue specimens. Shown is an example of a high-grade serous EOC tissue specimen. Arrows point to the RRM2 positively stained EOC cells.