SOX3 is an X-linked transcription factor essential for hypothalamo-pituitary axis formation and neural development 1. As a SOXB1 group member, SOX3 maintains neural progenitor identity by suppressing neuronal differentiation through counteraction of proneural proteins 2. During development, SOX3 expression is regulated by retinoic acid signaling through specific response elements in its promoter 3, with distinctive epigenetic signatures involving DNA methylation and histone modifications 2. SOX3 is critical for craniofacial morphogenesis and male sex determination, directing supporting cell precursor differentiation toward Sertoli cells 4. Loss-of-function mutations cause X-linked hypopituitarism with variable severity, ranging from isolated growth hormone deficiency to panhypopituitarism, often accompanied by ectopic posterior pituitary or persistent craniopharyngeal canal 5. In cleft lip/palate pathogenesis, SOX3 protein levels are significantly decreased, implicating it in orofacial development 4. Beyond developmental roles, SOX3 exhibits aberrant expression in multiple cancers including breast, gastric, hepatocellular, and esophageal carcinomas, modulating apoptosis, epithelial-mesenchymal transition, and cell proliferation 6. SOX3 also functions in immune regulation, with its motifs present in exhaustion-specific enhancers controlling PD-1 expression in CD8+ T cells 7.