SSX2 and neoplasm: Although molecular characterization of SS and the role of SYT-SSX are beginning to provide insight into events that may be important in shaping the biological behavior of the tumor, numerous questions remain, including whether or not SYT-SSX expression is sufficient for tumor formation and/or differentiation, the nature of the downstream targets of SYT-SSX, and what additional genes might be critical for the genesis of SS.