These changes in immune cell frequency, increases in tumor specific cytotoxic T-cells and reductions in immunosuppressive macrophages and MDSCs, with PBT treatment in C57Bl/6 mice or in GCN2-knockouts suggested that polyamine-dependent signaling through GCN2 is playing a key role in regulating the immune response to the tumor. This evidence concerns the gene EIF2AK4 and neoplasm.