KLK1 and ulcerative colitis: 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).