Dictionary.net

Proteins, usually found in the nucleus, that specifically bind thyroid hormones and regulate DNA transcription. These proteins, termed c-erbA, are activated by hormones and cause differentiation of erythroid progenitor cells which irreversibly lose proliferative potential. Thus c-erbA proteins act as growth suppressors. The c-erbA proteins are encoded by at least two genes, c-erbA alpha and c-erbA beta. Each of these has two isoforms. Mutations in the ligand-binding domain of the beta form causes THYROID HORMONE RESISTANCE SYNDROME.