JUNB is a proto-oncogene encoding an AP-1 transcription factor subunit that plays critical roles in cellular differentiation, immune responses, and disease pathogenesis. As part of the AP-1 complex, JUNB heterodimerizes with FOS family proteins to regulate gene transcription by binding to DNA consensus sequences 1. In cancer contexts, JUNB promotes tumor immune evasion by downregulating FasL and TRAIL death receptors while upregulating anti-apoptotic BCL2A1 and activating NF-κB signaling pathways 1. The protein drives metabolic reprogramming in triple-negative breast cancer through the NAT10-ac4C-JUNB-LDHA pathway, enhancing glycolysis and creating immunosuppressive tumor microenvironments 2. JUNB also mediates CAR-T cell exhaustion and terminal differentiation via MAPK signaling, where MEK inhibition downregulates JUNB-driven gene profiles associated with exhaustion, anergy, and apoptosis 3. In autoimmune diseases, JUNB partners with SUB1 to amplify DOCK2 transcription, promoting pathogenic T cell trafficking and tissue infiltration 4. Additionally, JUNB participates in fibrotic processes, being activated by TGF-β1 signaling in hepatic fibrosis and contributing to fibroblast-to-myofibroblast differentiation through STAT3-mediated super enhancer formation 56. These diverse functions establish JUNB as a key therapeutic target across multiple disease contexts.