Because MAV develops in only 60–70% of wild-type mice and becomes apparent 30 d after tumor excision, we tracked antigen-specific T cell responses by adoptively transferring Thy1.1-marked CD8 T cells expressing the Pmel T cell receptor that recognizes gp10025–33 melanocyte antigen and pre-activated to allow retroviral expression of PpyRE9 luciferase reporter gene (Luc+Pmel) (Fig 5A). The gene discussed is CD8A; the disease is neoplasm.