Synthetic pro-apoptotic BH3-peptides were applied to permeabilize MDS/AML blast cells (defined by CD45 lo-mid/SSC-low and CD34 expression) to assess the overall apoptotic priming and to specifically evaluate the impact of the main anti-apoptotic BCL-2 family proteins on cell survival. The gene discussed is PTPRC; the disease is acute myeloid leukemia.