CD26 and/or dipeptidyl peptidase 4 inhibitors can prevent colon cancer and lung metastasis in animal models (Angevin et al., 2017; Jang et al., 2015; Femia et al., 2013; Yorifuji et al., 2016), although epidemiological studies in humans are not clear (Enz et al., 2019). The gene discussed is DPP4; the disease is malignant colon neoplasm.