MLL-AF9 translocated cells display specific cytokine dependence profiles. (A) MLL-AF9–rearranged cells cultured in the presence of SR-1 and UM729 plus the indicated single cytokines were quantified by trypan blue dye exclusion after 3 days and compared with control (all cytokines, blue bar). (B) Cells cultured with IL-3 or SCF were additionally cultured for 7 and 17 days in the presence of SR-1, UM729, the respective cytokines IL-3 or SCF, and the indicated single cytokine to evaluate their sensitivity compared with the control (all cytokines, blue bar). Error bars indicate SEM for 2 analyses. (C) Flow cytometry profiles show representative phenotypes of cells cultured in the indicated cytokine milieus after 27 days (blue lines) vs cells culture in the complete cytokine cocktail (red shading). TPO, thrombopoietin.