Immunotherapy using tumour cells transduced with single-chain interleukin-12 (IL-12) protein has shown promise in murine models of neuroblastoma (Lode et al, 1998b), an effect that was enhanced in combination with tumour-targeted interleukin-2 (IL-2) protein (Lode et al, 1999). Here, IL2 is linked to neuroblastoma.