It has been found that intragastric GLP administration can restore the immune functions of intestinal mucosae disrupted by 5-fluorouracil (5-FU) in H22 tumor cell-bearing mice, thereby increasing the number of CD8+ T cells and elevating the expression of immunoglobulin A, TNF-α, and IL-2 in the ileum. This evidence concerns the gene CD8A and neoplasm.