Response of clinical leukemia and cultured Jurkat cells to treatment with pancratistatin. The apoptotic effect of 24 h exposure to 1 μM pancratistatin was observed by microscopy using cell-permeable Hoechst dye. Compared to the nuclear morphology of untreated cells (A, B), treatment with pancratistatin resulted in apoptosis characterized by condensed, brightly stained nuclei in Jurkat (E) and patient obtained leukemic PBMCs (F). Annexin-V binding, another characteristic feature of apoptosis, was minimal in untreated cells (C, D) in contrast to the binding observed after pancratistatin treatment (G, H). Hoechst and Annexin-V images are not of the same field.