Interestingly, both NQO1 and GSTP1 expression levels were higher in colon and lung cancers as well as compared to the normal tissues (Additional file 1: Supplement Fig. 6A and B), which was also reported in a previous study [44, 45], though no significant influence on stomach cancer was found (Additional file 1: Supplement Fig. 6C). Here, GSTP1 is linked to gastric cancer.