RETNLB (resistin-like beta) is a secreted protein predominantly expressed in intestinal goblet cells that plays a critical role in mucosal barrier function and defense. Primary function: RETNLB is a goblet cell-derived protein that contributes to intestinal homeostasis through mucus barrier strengthening 1. Mechanism: RETNLB secretion is regulated by multiple pathways including cathelicidin-mediated ROS production 2, IL-13 signaling during helminth infection 1, and dietary prebiotic stimulation 3. The protein belongs to the XCP/FIZZ/Resistin gene family encoding short secreted proteins with a conserved ten-cysteine motif 4. Disease relevance: High RETNLB expression is associated with oral squamous cell carcinoma progression through activation of Toll-like receptor 2/4/ERK signaling pathways; knockdown significantly reduces cancer cell viability, mobility, and invasiveness 5. Clinical significance: RETNLB upregulation during small intestinal helminth infection represents a conserved mucus-strengthening mechanism proposed for treating ulcerative colitis 1, suggesting therapeutic potential for inflammatory bowel diseases through mucosal barrier enhancement.