To address the hypothesis regarding whether apoptosis in MDS progenitor cell occurs during the early stage or at a differentiation stage, a post hoc analysis was performed to examine the apoptotic activity of caspase-3 in CD34 + cells, representing early progenitors, and in CD33 + and CD41 + cells, representing differentiated progenitors. The gene discussed is CD34; the disease is myelodysplastic syndrome.