Characterization of EB-PE cells. (A) EB-PE cells after Giemsa staining. (B) Northern blot analysis. RNA was prepared from EB-PE cells and used for globin gene expression analysis. Each lane contains 10 μg of total RNA. Probes used are as follows: lane 1, ζ globin; lane 2, β-major; lane 3, βH1. GAPDH is shown as a loading control. (C) EB-PE colony assay in various growth factor combination. EB-PE cells (5 × 10³ cells/mL) were plated in methylcellulose culture containing different combinations of growth factors (Epo [2 U/mL]; KL [10 ng/mL]/Epo; KL [100 ng/mL]/Epo; IL-3 [10 ng/mL]/IL-11 [10 ng/mL]/Epo; and IL-3 (10 ng/mL)/GM-CSF [5 ng/mL]/M-CSF [5 ng/mL]). Error bars indicate standard deviation of numbers obtained from 3 different plates. (D) Two types of colonies that develop in cultures containing Epo are shown. One consists of 20 to 40 cells per colony and the other 100 to 300 cells per colony.