CD8 T cells derived from GREAT-OT1-Thy1.1 mice (IFN-γ-IRES-eYFP-OT-1 T cells), which exhibit YFP fluorescence signal upon IFN-γ production, were activated ex vivo and transferred to mTmG mice (expressing Thy1.2) bearing MCA-205-OVA-GFP tumor. The gene discussed is CD8A; the disease is neoplasm.