Although erythroid progenitors appear to be the principal EPO -responsive cell type in vivo due to the restricted expression of the EPOR , many growth factor-dependent cell lines expressing the EPOR can respond to EPO by activating many or all of these pathways .
although erythroid progenitors appear to be the principal epo -responsive cell type in vivo due to the restricted expression of the epor , many growth factor-dependent cell lines expressing the epor can respond to epo by activating many or all of these pathways .
O B-cell_type I-cell_type O O O O O B-protein_family_or_group O O O O O O O O O O O O B-protein_family_or_group O O B-cell_line I-cell_line I-cell_line I-cell_line O O B-protein_family_or_group O O O B-protein_family_or_group O O O O O O O O O