IFNG and acute lymphoblastic leukemia: The induction of cell death in six B-cell precursor ALL cell lines (MHH-CALL-4, NALM-6, REH, RS4;11, NALM-16, KOPN-8) incubated with different concentrations of TNF-α (0.1 ng/ml,1 ng/ml, 10 ng/ml, 100 ng/ml) and IFN-γ (0.1 ng/ml, 1 ng/ml, 10 ng/ml, 100 ng/ml) was examined alone and in combination at multiple points in time (24 h, 48 h, 72 h).