Substitution promoters were then generated where the entire X-box , or only the X1- or X2- boxes of HLA-DRA were replaced with the analogous regions of HLA-DQB .
substitution promoters were then generated where the entire x-box , or only the x1- or x2- boxes of hla-dra were replaced with the analogous regions of hla-dqb .
O O O O O O O O B-DNA_domain_or_region O O O O O O O O O B-DNA_domain_or_region O O O O O O O B-DNA_domain_or_region O