IFNγ renders caspase-8- and Fas-deficient NBLs sensitive to FasL. A. The indicated cell lines were treated with 100 ng/ml interferon-γ (IFNγ) or were left untreated (UT) for 24 h. Cells were then treated or not for 24 h with 100 ng/ml TNFα and Fas expression was analyzed by cytometry using a PE-conjugated Fas or an isotype antibody. B. Fas and caspase-8 expression analysis by Western blot in the indicated cell lines pre-treated for 24 h with 100 ng/ml interferon-γ (IFNγ) and treated with 100 ng/ml TNFα for 24 h. C. Cell death assay in NBL cell lines pre-treated or not (UT) with 100 ng/ml IFNγ for 24 h and thereafter treated or not with 100 ng/ml TNFα for 24 h. Next, cells were treated for an additional 24 h with 100 ng/ml Fc:hFasL. *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001.