We collected 4 stages of colorectal cancer progression from the clinic, 5 patients in each stage, a total of 20 patients, and analyzed the KLK1 expression level with the intestinal barrier integrity marker ZO‐1 and the validation score of ulcerative colitis patients: Immunohistochemistry (IHC) of pathological sections confirmed that KLK1 and ZO‐1 protein levels were expressed most highly in healthy controls, and KLK1 expression decreased significantly with inflammatory cancer transformation (Figure 6K–M). This evidence concerns the gene KLK1 and colorectal cancer.