A lymphoid-specific element , microB , is necessary for enhancer function in pre-B cells .
a lymphoid-specific element , microb , is necessary for enhancer function in pre-b cells .
O B-DNA_domain_or_region I-DNA_domain_or_region O B-DNA_domain_or_region O O O O B-DNA_domain_or_region O O B-cell_type I-cell_type O