Knock-down of Spi-1 arrests proerythroblasts expansion. (A) Cells were seeded at 10⁴ cells/mL in liquid medium with dox (100 ng/mL) or without. Living cells were counted at days (d) indicated using trypan blue exclusion test. Data are mean ± SD of at least 8 experiments. The percentage of Spi-1 expression relative to untreated cells is indicated under the histograms. (B) Five days after dox treatment, cells were diluted to 5 × 10⁴ cell/mL in medium with or without dox, and living cells were counted 24 hours (+d1) and 48 hours (+d2) later by trypan blue exclusion test. Data are the mean ± SD of 3 experiments.