GCs stimulate stress erythropoiesis by enhancing erythroblast output predominantly from BFU-E progenitors. We determined whether adding 100nM Dex changes the maximum number of erythroblasts that sorted CFU-E and BFU-E cells produce in SFELE medium with or without 100nM Dex. (A) Production of erythroblasts from sorted CFU-E (CD71^20%high) cells peaks at day 3 with 28- and 15-fold expansion with and without Dex, respectively (n = 4). Error bars show 1 SD. (B) BFU-E (CD71^10%low) cells cultured with 100nM Dex expand 8800-fold (13 cell divisions) with a peak at day 8 and expand 650-fold (9 cell divisions) without Dex with the peak at day 5 (n = 5). At the endpoint of the BFU-E cell cultures cells were routinely stained with May-Grünewald-Giemsa stain, which consistently showed that virtually all cells were erythroblasts equivalent to the cells depicted in Figure 6C (data not shown). Error bars show 1 SD.