GADD45B (growth arrest and DNA damage inducible beta) is a stress-responsive protein that regulates cell cycle arrest, apoptosis, and inflammatory responses. The protein functions as a tumor suppressor by inhibiting cell proliferation and promoting apoptosis through activation of MAPK signaling pathways, particularly p38 and JNK cascades 1. GADD45B mediates cellular responses to DNA damage and stress by interacting with transcription factors like FOS to promote cellular senescence 2. In disease contexts, GADD45B expression is dysregulated across multiple conditions. It is significantly upregulated in COPD patients, where it facilitates airway inflammation and epithelial cell senescence through p38 phosphorylation and FOS interaction 2. Conversely, GADD45B is downregulated in skin cutaneous melanoma, where higher expression correlates with better prognosis and enhanced immune cell infiltration, particularly promoting M1 macrophage polarization 3. The protein has been identified as a biomarker in various diseases including osteoarthritis 4, IgA nephropathy 5, and aortic dissection 6. Epigenetic regulation of GADD45B involves DNA methylation status and histone modifications, with therapeutic compounds like shikonin capable of reactivating its tumor suppressor functions 17.