Background: SART1 (squamous cell carcinoma antigen recognized by T cells 1) was originally identified as a gene that encodes an antigenic peptide expressed in squamous cell carcinomas and recognized by cytotoxic T lymphocytes. The SART1 gene encodes two proteins, SART1(800) and SART1(259). SART1(800) has been found to be expressed in the nucleus of the majority of proliferating cells and has been identified as a component of the splicesomal complex required for U4/U6.U5 tri-snRNP recruitment and the assembly of mature splicesomes.