SPAG6 and testicular germ cell tumor: In addition, it has also been detected in the inner ear hair cells, lung bronchial cells, ovarian epithelial cells, lymphocytes, and fibroblasts,6, 7 as well as in testicular germ cell tumors, hematological malignancies, breast and lung cancer, and bladder cancer.1, 8, 9 In this review, we focus on the function of SPAG6 in various cells and the molecular mechanism involved in SPAG6-mediated tumorigenesis and progression.