Time course of initiation of tumor growth in mock-immunized mice and mice vaccinated with irradiated, GM-CSF/IL-12–transfected MPC11 cells. Mice were vaccinated with irradiated MPC11 cells with or without cytokine gene transfection. Both MPC11 and MPC11Dox10-1 cells were used for tumor challenge. Tumor growth was monitored for up to 35 days. Data shown represent cumulative results of three independent experiments (n = 15).