Proliferation of t(11;17)-positive leukemia cells in response to G-CSF and ATRA. Mononuclear cells, consisting of more than 90% of leukemic cells, were isolated from the peripheral blood at first diagnosis. Cells were cultured at 2 × 10⁵ cells/mL with medium alone, G-CSF (0.1 μg/mL), ATRA (10⁻⁶mol/L), or with a combination of ATRA and G-CSF. At the indicated times cell numbers were counted. Values represent the mean of triplicate measurements.