This gene belongs to the family of highly homologous synovial sarcoma X (SSX) breakpoint proteins. These proteins may function as transcriptional repressors. They are also capable of eliciting spontaneously humoral and cellular immune responses in cancer patients, and are potentially useful targets in cancer vaccine-based immunotherapy. SSX1, SSX2 and SSX4 genes have been involved in the t(X;18) translocation characteristically found in all synovial sarcomas. This gene is classified as a pseudogene because a splice donor in the 3' UTR has changed compared to other family members, rendering the transcript a candidate for nonsense-mediated mRNA decay (NMD). [provided by RefSeq, Aug 2009].