Factors that can initiate an apoptotic signaling cascade, such as Fas, Fas-L, tumor necrosis factor-a, and tumor necrosis factor-related apoptosis initiating ligand, are upregulated in bone marrow cells of MDS patients [37, 38], and it is thought that this increase in apoptosis in the bone marrow may contribute to the cytopenias that are a hallmark of MDS [39]. The gene discussed is FAS; the disease is myelodysplastic syndrome.