CYP2C19 and colonic neoplasm: Moreover, previous studies have shown that CYP3A4 was significantly downregulated in colonic tumors compared with normal mucosa tissues, whereas CYP2C19 and CYP2C9 were highly expressed in colon cancer; thus, upregulating CYP3A4 expression and downregulating CYP2C19 and CYP2C9 expression may prohibit the growth and metastasis of colon cancer cells [81,82].