Efficacy of VSV virotherapy in syngeneic mouse tumour models has been described both in tumours highly susceptible for VSV infection34 as well as in models with limited viral replication within the tumour tissue.25 To address whether the interferon response of LLC1 cells correlates with oncolytic VSV-GP efficacy in vivo, we compared the treatment outcome in subcutaneous LLC1 and LLC1-IFNAR1−/− tumours in syngeneic C57BL/6J mice. The gene discussed is IFNAR1; the disease is neoplasm.