A relatively low level of OCT4 expression was found in clear cell carcinoma, while a large percent of serous carcinoma had a higher level of OCT4 when compared with endometrioid adenocarcinoma and mucinous cystadenocarcinoma, all of which showed positive staining for OCT4 (Fig. 1C). This evidence concerns the gene POU5F1 and mucinous cystadenocarcinoma.