SCGB1A1 (secretoglobin family 1A member 1), also known as club cell secretory protein (CCSP), encodes one of the most abundant proteins in the lung, primarily produced by club cells of the distal airway epithelium 1. The protein binds phosphatidylcholine and phosphatidylinositol and acts as a potent inhibitor of phospholipase A2, conferring anti-inflammatory properties 1. SCGB1A1 is differentially expressed across airway regions, with high expression in tracheobronchial airways 2. Mechanistically, SCGB1A1 expression is regulated by FOXA2, a transcription factor downregulated in asthma 3. CC16 protein signals through VLA-2 integrin to enhance epithelial antimicrobial responses including SPLUNC1 expression 4. Clinically, reduced SCGB1A1 levels are associated with obstructive lung diseases including asthma and COPD 1, while the SCGB1A1 +38A/G polymorphism increases asthma risk 5. SCGB1A1-knockout mice show increased airway hyperreactivity and inflammation following allergen exposure 3. SCGB1A1 serves as a biomarker for airway epithelial integrity and represents a potential therapeutic target for inflammatory lung diseases.