Effects of overexpression of EPOR on the EPO-induced erythroid differentiation of UT-7/GM cells. (A) Parent UT-7/GM and UT-7/GM-EPOR cells were treated with EPO (10 U/mL) for 7 days, and total cellular RNA was isolated. The transcripts of EPOR, ALAS-E, and γ-globin were examined by Northern blotting. The membrane was rehybridized with a ³²P-labeled human ribosomal DNA probe to show the amounts of RNA loaded. (B) Dianisidine-staining. UT-7/GM-EPOR cells were cultured with 10 U/mL of EPO for 7 days. The cells were harvested for dianisidine staining. The data are the mean ± SD of triplicate cultures. (C) Parent UT-7/GM cells and UT-7/GM-EPOR cells were starved for 24 hours. The cells were stimulated with GM-CSF (10 ng/mL, left panel) or EPO (10 U/mL, right panel) and harvested for cell cycle analysis. The percentage of cells in G0/G1 was determined. The data are the means of three independent experiments.