Comparing mean growth (inhibition) graphs of NQO1 substrates, the greatest cytotoxicity is towards solid tumour cell lines, including most melanoma, non-small cell lung, and colon cancer cell lines, with negligible toxicity towards leukemic cell lines, in contrast with the strong anti-leukemic activity of TrxR inhibitors (see Supplementary Materials). Here, NQO1 is linked to malignant colon neoplasm.