Using E8I-cre that specifically targeted CD8+ T cells, it was shown that E8Icre; Notch2fl/fl mice died faster than E8Icre; Notch1fl/fl after inoculation of ovalbumin-expressing thymoma; treatment with Notch2 agonist antibody or infusing dendritic cells overexpressing Dll1 further boosted the anti-tumor CD8+ T cell responses. This evidence concerns the gene DLL1 and neoplasm.