By studying the effect of common anti-cancer drugs on T-cell leukemia Jurkat cells with knocked out genes for key proteins of external apoptosis and necroptosis, we found out that FAS-associated death domain protein (FADD) and at least one of the effector caspases (i.e., 3, 6, and 7) are indispensable for the cell death execution. This evidence concerns the gene FADD and T-cell leukemia.