The two proteins differ by a 14-amino acid serine-rich insertion present in one of the CREB isoforms .
the two proteins differ by a 14-amino acid serine-rich insertion present in one of the creb isoforms .
O O O O O O B-protein_domain_or_region I-protein_domain_or_region I-protein_domain_or_region I-protein_domain_or_region O O O O O B-protein_molecule O O