VANGL1 and cancer: A mammalian homologue of Drosophila VANGL1, KAI1 COOH-terminal interacting tetraspanin (KITENIN), has been shown to bind KAI1/CD82 via its COOH-terminal region [7], and to increase tumor invasiveness, cancer progression, stem cell and epithelial-mesenchymal transition (EMT) marker expression, and metastasis [8–15].