Truncation of the beta globin promoter led to a 2-3 fold increase in promoter activity .
truncation of the beta globin promoter led to a 2-3 fold increase in promoter activity .
O O O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O O O O O O O B-other_name I-other_name O