TKT and neoplasm: To examine whether the adaptive tumor-specific immune responses may be modulated by the PsV-TK/GCV suicide gene therapy in vivo, an antigen specifically expressed by MB49 tumor cells, the minor histocompatibility male antigen HY (Uty) [23] and the known H-2Db epitope Uty246–254 [24] were used to measure the anti-tumor CD8 T-cell responses.