NQO2 and malignant colon neoplasm: A setof meta-substituted 3-arylisoquinolinoneshave been identified that show substantial cytotoxicity in breast,liver, lung and colon cancer cell lines; these are up to 700-foldmore active than the corresponding para analogues.These compounds were initially proposed as inhibitors of N-ribosyl dihydronicotinamide (NRH): quinone oxidoreductase 2 (NQO2)but were found to be inactive against the enzyme.