We used mouse embryonic stem ( ES ) cells to study globin gene expression and switching in vitro .
we used mouse embryonic stem ( es ) cells to study globin gene expression and switching in vitro .
O O B-cell_type I-cell_type I-cell_type I-cell_type I-cell_type I-cell_type I-cell_type O O B-DNA_family_or_group I-DNA_family_or_group O O O O O O