NQO1 and colonic neoplasm: Mikami K et al. reported that the expression and enzyme activity of NQO1 is not only upregulated in colon cancer cell lines and colorectal tumors, but also significantly greater in tumors with nodal metastases than those without metastases[26], while Gan et al. reported higher expression of NQO1 protein in lower-grade and superficial bladder tumors compared with high-grade and invasive tumors[27].