ST1326 induces a dose- and time-dependent apoptosis in primary cells from hematopoietic disease. AML, acute lymphoblastic leukemia (B-ALL), and chronic lymphoblastic leukemia (CLL) primary cells were exposed to the indicated concentrations of ST1326. Apoptosis induction was assessed by Ann V/propidium iodide (PI) staining (see supplemental Materials and methods). Percentages of Ann V–positive cells and Ann V–positive/PI cells are shown. Cell counts and viability were assessed at the indicated time points by trypan blue exclusion counting.