GLCCI1 (glucocorticoid-induced transcript 1) is a cytoplasmic protein that functions as a glucocorticoid-responsive mediator with multiple roles in immune regulation and asthma pathophysiology. Primary function: GLCCI1 acts as an antiapoptotic protector in T cells by binding to dynein light chain LC8 and inhibiting PAK1 kinase activity, thereby protecting thymocytes from glucocorticoid-induced apoptosis 1. Mechanism: The protein regulates autophagy in airway epithelial cells by binding WDR45B and inhibiting its expression 2, and activates NRF2 antioxidant signaling through the DYRK1A/FAM117B axis to ameliorate mitochondrial dysfunction 3. Disease relevance: Reduced GLCCI1 expression and hypermethylation of GLCCI1 gene body are associated with asthma severity 4 and predict future asthma exacerbations 5. Clinical significance: The GLCCI1 rs37973 genetic variant significantly affects inhaled corticosteroid efficacy; patients carrying the G allele show diminished lung function improvement during ICS treatment 6. Additionally, GLCCI1 fusion with BRAF has been identified in pheochromocytomatosis, activating MAPK signaling 7. These findings identify GLCCI1 as a potential therapeutic target in asthma management and a biomarker for corticosteroid responsiveness.