The DNA-associated protein encoded by the PHOX2B gene is a member of the paired family of homeobox proteins localized to the nucleus. The protein functions as a transcription factor involved in the development of several major noradrenergic neuron populations and the determination of neurotransmitter phenotype. The gene product is linked to enhancement of second messenger-mediated activation of the dopamine beta-hydroylase, c-fos promoters and several enhancers, including cyclic amp-response element and serum-response element.Synonyms: NBPhox, Neuroblastoma Phox, PHOX2B homeodomain protein, PMX2B, Paired mesoderm homeobox protein 2B, Paired-like homeobox 2B