Several mutants derived from transformed human B cell lines are defective in expressing major histocompatibility complex ( MHC ) class II genes .
several mutants derived from transformed human b cell lines are defective in expressing major histocompatibility complex ( mhc ) class ii genes .
O O O O B-cell_line I-cell_line I-cell_line I-cell_line I-cell_line O O O O B-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group I-DNA_family_or_group O