Present in high molecular weight complexes in tumor cells. Interacts with SDCBP2 (PubMed:11102519). Colocalizes with SDCBP2 in the apical region of the cell (PubMed:11102519). Highly expressed in lung, breast, colon and ovarian carcinomas. It is also present on some normal cells, endothelial cells in particular. Belongs to the L6 tetraspanin family.