After treatment with metformin, the cell cycle of CRC cells was significantly arrested at the G1 phase; the expression of the AMPK, p53, and p21 proteins was upregulated; the expression of the CPS1, ARG1, OTC, and ODC proteins was downregulated; and the putrescine levels in HCT116 xenografts and HCT116 cells were decreased. The gene discussed is ODC1; the disease is colorectal carcinoma.