POU2F2 and synovial sarcoma: We selected three candidate markers for detailed study comprising the OCT2 (octamer binding protein 2; also known as POU2F2) transcription factor, which was previously described as being expressed in B cells [15], and two cancer testis antigens, SSX gene family (synovial sarcoma X chromosome breakpoint) and SAGE1 (sarcoma antigen 1) [16,17].