The gene encoding human Membralin, C19orf6, localizes to chromosome 19p13.3. It contains 11 exons, which encode at least two splice variants in human cancer. Membralin is a multi-pass membrane protein and exists either as a long or short form. The long form of Membralin comprises all 11 exons, while the short form contains all exons except exon 10. Expression of different Membralin isoforms depends on tissue type. The long form is expressed in ovarian and colorectal carcinomas, whereas the short form is expressed in breast or pancreatic carcinomas. Because Membralin expression in ovarian carcinomas is highest in serous carcinomas as compared to surface epithelium carcinomas, expression of Membralin may be useful as a novel tumor-associated marker in ovarian serous carcinomas.