Upregulation of ATAD2 protein expression in OC compared with non-cancerous normal tissues and ovarian metastases from the stomach. Representative IHC images showing the expression levels of ATAD2 in (A) primary OC tissues, (B) adjacent normal ovarian tissues (C) and metastatic ovarian cancer from the stomach. (D) Comparison of the ATAD2 IHC scores in primary OC, adjacent normal and in gastric metastases to the ovaries. *P<0.05 and ****P<0.0001 (E) Expression of ATAD2 in different types of OC tissues. Comparison was performed between serous adenocarcinoma samples and non-serous samples of clear cell carcinoma, dysgerminoma and endodermal sinus carcinoma. **P<0.01 vs. endodermal sinus carcinoma. Scale bar, 100 µm. OC, ovarian cancer; IHC, immunohistochemistry; ATAD2, ATPase family AAA domain-containing protein 2.