MUC2, a secretory mucin, is the major macromolecular component of mucus generated by goblet cells. Its primary function is to form a protective mucus barrier between epithelial surfaces and the gut lumen, playing a crucial role in gut barrier function and homeostasis. The production of MUC2 is regulated by various bioactive molecules, signaling pathways, and gut microbiota, forming a complex regulatory network [2].

In ulcerative colitis (UC), the MUC2 mucus barrier is dysfunctional. Bacterial factors related to the MUC2 mucus barrier are involved in the response to dietary changes, contact stimulation with colonic epithelial cells, and mucosal and submucosal inflammation during UC's development [1].

In colorectal cancer (CRC), MUC2 expression is disrupted. Its alterations are associated with immunomodulation, differences in tumor immunity, and microbiota regulation. MUC2 may also act as a physical barrier to immune infiltration in CRC [3,5].

In breast cancer, MUC2 mediates cell proliferation, apoptosis, and metastasis [4].

In conclusion, MUC2 is essential for maintaining gut barrier function and homeostasis. Studies, including those using potential gene knockout models, have revealed its significance in diseases such as ulcerative colitis, colorectal cancer, and breast cancer, providing insights into disease mechanisms and potential therapeutic targets.