The failure to express a class II gene in at least one such mutant line has been mapped to the MHC class II X box , a conserved transcriptional element in the promoter region .
the failure to express a class ii gene in at least one such mutant line has been mapped to the mhc class ii x box , a conserved transcriptional element in the promoter region .
O O O O O B-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group O O O O O B-cell_line I-cell_line O O O O O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O O B-DNA_domain_or_region I-DNA_domain_or_region O