FAS and breast cancer: Furthermore, the significant increase in NK cell-mediated apoptosis of spheroids following cytokine-treatment was confirmed by the caspase 3/7 assay (Fig. 7D, H), thus suggesting an activation of the NK cell-mediated apoptosis by the upregulation of FAS and TRAIL-R2 on IFN-γ + TNF-α-treated BC spheroids, as reported above (Fig. 6).