tokens: Site directed mutagenesis of binding sites for the repressor proteins BP1 and BP2 in the upstream portion of the beta globin gene flanking region led to a 4-6 fold increase in promoter activity .
folded_tokens: site direct mutagenesis of bind site for the repressor protein bp1 and bp2 in the upstream portion of the beta globin gene flanking region lead to a 4-6 fold increase in promoter activity .