MUC7 is a secreted, low-molecular-weight mucin glycoprotein that serves critical protective functions in respiratory and oral cavities. The protein functions as part of the innate immune system, with its primary role being antimicrobial defense 1. Unlike gel-forming mucins, MUC7 is secreted but does not polymerize, distinguishing it from other respiratory mucins like MUC5AC and MUC5B 1. The gene exhibits tissue-specific expression patterns, being constitutively expressed in salivary glands and human lung epithelial cells 23. In bronchial airways, MUC7 is specifically expressed in serous tubules of submucosal glands, showing functional diversity between different glands 3. The protein undergoes rapid proteolytic degradation in saliva, particularly at its N-terminal region which contains antimicrobial activity, with desialylation serving as a prerequisite for this degradation 4. MUC7 expression is regulated by inflammatory signals, with TNF-α upregulating transcription through NF-κB signaling pathways 2. Recent studies suggest diagnostic potential, as MUC7 expression shows promise as a biomarker for bladder cancer with high specificity (92%) 5. The gene is located on chromosome 4-q21 and shows limited genetic polymorphism 67.