MAX (MYC associated transcriptional regulator X) is a transcriptional regulator that functions as a central component of the MYC/MAX/MXD1 network by forming sequence-specific DNA-binding heterodimers with either MYC or MAD proteins 1. Unlike MYC, MAX expression remains relatively stable and is not significantly modulated during cell proliferation or differentiation, with MAX RNA showing a half-life greater than 3 hours 2. MAX can form homodimers or heterodimerize with MYC to create transcriptionally active complexes, while MAX-MAD complexes act as transcriptional repressors 1. The protein competes with MYC for MAX binding and can inhibit MYC transformation activity 3. Overexpression of MAX promotes erythroid differentiation and confers resistance to drug-mediated apoptosis by reducing functional MYC/MAX complexes relative to MAX/MAX dimers 3. MAX expression can be positively regulated by retinoic acid through transcriptional mechanisms 4. Clinically, germline MAX mutations are associated with hereditary pheochromocytoma, supporting MAX's role as a negative regulator of the MYC network and suggesting that MYC deregulation contributes to hereditary cancer predisposition 1. The MAX gene is located on chromosome 14, a region involved in various hematologic malignancies 2.