However, chronic gastritis associated with Hp infection may evolve into intestinal metaplasia (IM), which can be classified into two categories based on histomorphological features: complete type, which is characterized by significant loss of the expression of MUC1; MUC5Ac; and MUC6, and accompanied by abnormal expression of MUC2; incomplete type characterized by the simultaneous expression of MUC1, MUC5AC, and MUC6, and accompanied by abnormal expression of MUC2; IM will further deteriorate and develop into gastric adenocarcinoma (Figure 3) [94,95]. Here, MUC5AC is linked to chronic gastritis.