WFDC2 and ovarian serous adenocarcinoma: Drapkin et al (15) investigated the expression of HE4 in various types of ovarian cancer organization using an immunohistochemical method and observed that HE4 was expressed in 50% of ovarian clear cell carcinomas, 93% of ovarian serous ovarian cancer and 100% of endometrioid carcinomas of the ovary.