FAS and neuroblastoma: In the search for clinical approaches that lead to the upregulation of Fas and PVR, thereby rendering NB cells more susceptible to NK-cell-mediated killing, we tested the efficacy of the two cytokines IFNγ and TNFα, known to upregulate Fas [47,48,49,50,51,52] in different contexts through the activation of NF-Kb [53,54].