KDM4B is robustly expressed in ovarian cancer tissue and ovarian cancer cell lines compared with normal ovarian surface epithelial cells. (a) Representative immunohistochemical (IHC) detection of KDM4B (top row; brown, DAB; blue, hematoxylin) in tumor microarray sections from normal ovary and high-grade ovarian serous adenocarcinoma biopsies with matched primary and metastatic tumor sections. IgG (middle) and H&E (hematoxylin and eosin, bottom) serve as controls for nonspecific DAB staining and tissue structure controls, respectively. (b) Representative IHC images of tumor sections with high (left) and low (right) KDM4B. For each image, the percentage of cancer cell nuclei staining positive for KDM4B is denoted in the lower left corner. For (a) and (b), scale bar for entire section, 100 μm; scale bar for inset, 50 μm. (c) Box-and-whisker plot of KDM4B nuclear staining in normal ovary (N, n=9), primary HGSA tumors (P, n=30) and metastases (M, n=29). Diamond, mean; significance of staining differences was determined using Kruskal–Wallis, with Mann–Whitney U-test (*P<0.001). (d) Percentage of total patient samples in each category (normal, primary and metastasis) staining for high or low KDM4B (high >10% nuclei staining positive for KDM4B, low <10%). (e) Correlation between KDM4B staining in metastases (n=29) compared with matched primary tumors (n=29). Significance determined by Spearman’s correlation. (f) KDM4B expression in representative normal ovarian surface epithelium. Scale bar, 100 μm.