So far, two groups have reported that CD80 or CD86 gene transfer in murine NB cells decreases their tumorigenicity (Katsanis et al, 1995; Enomoto et al, 1997), whereas virtually no data are available on the expression of costimulatory molecules in human NB cells (Uçar et al, 1995). The gene discussed is CD80; the disease is neuroblastoma.