These transfectants, which produced low amounts of the cytokine in culture supernatants, displayed dramatic reduction in their proliferation rate, increased expression of functional TNF-α binding sites, HLA and CD40 surface molecules, similarly to that observed in vitro following treatment of NB cell lines with hrIFN-γ (Ponzoni et al, 1992; Montaldo et al, 1994; Airoldi et al, 2003). Here, CD40 is linked to neuroblastoma.