Suzuki et al showed that CK20 was expressed only in epithelium of the gastrointestinal tract and urethral epithelium, while CK7 is expressed in ovarian tissues.[13] Ronnett et al found that primary ovarian mucinous tumors express CK7, rather than CK20, while patients with appendiceal malignancy are diagnosed with CK20-positive, and CK7 is expressed in 50% cases. This evidence concerns the gene KRT20 and ovarian mucinous neoplasm.