PHGDH and malignant colon neoplasm: We found that the expression levels SHMT2, PSAT1, PHGDH, PSPH, CBS, DAO, MAOA, AOC2, GNMT, PIPOX, ALAS2, AOC3 and MAOB were significantly increased in colon cancer tissues compared with those in normal tissues (Supplemental Fig. 2B).