SSX4 and cancer: Moreover, Gure et al. (1997) and Türeci et al. (1998) observed that the family members SSX1, SSX2, SSX4, and SSX5 were expressed in normal tissues only in the testis and in a wide variety of cancers, including melanoma, lymphoma, and head and neck, ovarian, colorectal, and breast cancers, whereas SSX3 was expressed in normal testicular tissues but not in cancer tissues [15,16].