Keap1-IN-1 (Compound 27) is the inhibitor for Keap1 , that covalently modifys the Cys151 site in the BTB domain of KEAP1, and interfers with the interaction between Keap-Nrf. Keap1-IN-1 upregulates the mRNA expression of the antioxidant stress element (ARE)-dependent gene NQO1 with an EC 50 of 160 nM. Keap1-IN-1 exhibits cytotoxicity in cell U2OS with an EC 50 of 527 nM.