Growth curves of cytokine treated bone marrow. Each culture was started with 1 × 10⁷ cells after depletion of plastic-adherent cells and incubated with either 100 U/mL GM-CSF or 100 U/mL IL-3. Number of the recovered cells of each time point represents mean ±SD (n = 3). •, adherent cells in GM-CSF culture; ▪, nonadherent cells in GM-CSF culture; ○, adherent cells in IL-3 culture; □, nonadherent cells in IL-3 culture.