Percentage of clones scored as LTC-ICs in each of the 7 cytokine combinations. Selected clones proliferating in round-bottomed 96-well plates seeded with individual G₀CD34⁺CD38^–/lo cells in the 7 cytokine combinations detailed in Table 1 were transferred to flat-bottomed 96-well plates on day 7 and assayed for LTC-IC function as described in “Materials and methods.” A total of 1776 clones were assayed for LTC-IC function and between 100 and 428 clones were examined for each cytokine combination. Data represent the percentage of clones in each group determined on day 49 to have originated from an LTC-IC.