ISG15 and neoplasm: To further validate our hypothesis that the therapeutic efficacy of Lm-LLO-ISG15 in CRC is mediated by the generation of an ISG15-specific anti-tumor immune response, we compared the anti-cancer potency of Lm-LLO-ISG15 with a Control Lm, i.e., a Listeria vaccine that does not secrete ISG15.