ARNT2 is a bHLH/PAS transcription factor that functions as a key regulator of neural development and cellular differentiation. Primary function: ARNT2 recognizes xenobiotic response elements (XREs) and controls transcription through heterodimerization with partner proteins 1. In the central nervous system, ARNT2 modulates affective empathy by regulating somatostatin-expressing interneurons in the anterior cingulate cortex, controlling pyramidal cell excitability and theta oscillations critical for emotion recognition and social behavior 2. ARNT2 also promotes osteogenic differentiation of mesenchymal stem cells while suppressing adipogenesis, interacting with HIF1A and other factors to influence bone homeostasis 3. Mechanism: ARNT2 functions as a transcriptional activator, binding directly to target promoters (e.g., STRA6) to regulate gene expression and downstream metabolic pathways 4. Disease relevance: ARNT2 mutations cause Webb-Dattani syndrome affecting hypothalamo-pituitary development. Loss of ARNT2 expression impairs craniofacial development, though no disease-causing mutations were detected in orofacial cleft cases 5. Clinical significance: ARNT2 functions as a tumor suppressor in hepatocellular carcinoma 6, non-small cell lung cancer 7, and retroperitoneal liposarcoma 4. High ARNT2 expression correlates with improved overall survival and reduced recurrence, making it a prognostic marker and therapeutic target for cancer treatment.