ND, not done.

CD34⁺CD38^low/neg cells were first exposed to cytokines for 4 days with or without MS5 cells. Cells that had completed 2 divisions in each condition were sorted and either assessed in LTC or cultured in the same medium with or without MS5 cells for an additional 2 days (see procedure in Figure 1). On day 6, cells that had divided 2 more times (4 divisions since day 0) were sorted and transferred to standard LTC-IC assays. Numbers refer to the number of LTC-IC–derived CFCs generated by 1000 cells sorted on day 4 (column 3) or on day 6 (column 5).