We previously showed that DT-GMCSF treatment of U937 cells, an AML cell line, causes activation of caspases and the induction of apoptosis [10]via a mechanism that involved the adaptor protein FADD, which regulates the extrinsic apoptotic pathway that is normally activated by ligand binding to death receptors (e.g. Fas/CD95 and the TRAIL receptors). The gene discussed is FAS; the disease is acute myeloid leukemia.