Given that CD26+ colorectal cancer stem cells (CSC) with metastatic properties are preferentially found in metastatic tissues and advanced colorectal cancers with poor prognosis [2], we hypothesized that CD26+ CSC are generated during the later stage of carcinogenesis, where the cancer cells acquire a new genetic aberration leading to a CD26+ phenotype. The gene discussed is DPP4; the disease is colorectal cancer.