Although PD-1 expression was not detected in CD8 T cells in lymphoid organs of naive mice one week after vaccination (data not shown) presumably due to the low frequency of Ag-specific cells induced by the vaccine, PD-1 was observed in tumor bearing mice, whose OVA(257–264) Tetramer+ frequencies ranged between 5 and 8%. The gene discussed is RENBP; the disease is neoplasm.