Could act as a modulator of transcription. Expressed at high level in the testis. Expressed at low level in thyroid. Not detected in tonsil, colon, lung, spleen, prostate, kidney, striated and smooth muscles. Detected in rhabdomyosarcoma and fibrosarcoma cell lines. Not detected in mesenchymal and epithelial cell lines. A chromosomal aberration involving SSX1 may be a cause of synovial sarcoma. Translocation t(X;18)(p11.2;q11.2). The translocation is specifically found in more than 80% of synovial sarcoma. The fusion products SSXT-SSX1 or SSXT-SSX2 are probably responsible for transforming activity. Heterogeneity in the position of the breakpoint can occur (low frequency). Belongs to the SSX family.