MPO and colorectal carcinoma: Consistent with these findings in animal models, we found that, in the Cancer Genome Atlas (TCGA) database, the expressions of the anti-oxidant genes (CAT, GSR, GSTA1, GSTM1, and HMOX1) are reduced, while the expression of pro-oxidant gene MPO is increased, in the tumor samples of human CRC patients (Lei et al., 2021).