Nox1-dependent ROS generation has been shown to play a pivotal role in cell signaling, cell growth, angiogenesis, motility and blood pressure regulation. ML171 strongly blocks ROS generation in HT29 cells (IC ₅₀ =0.129 μM) and only increasing over-expression of Nox1 can overcome the blockage of ROS generation caused by ML171 treatment in HEK293 cell system reconstituted with all the components required Nox1-dependent ROS generation. ML171 efficiently blocks ROS production measured by carboxy-H2-DCFDA staining as well as DPI used as a positive control. When ML171 is tested in HEK293-Nox1 reconstituted cell system, higher potency in blocking Nox1-dependent ROS generation is observed compared with the parental compound.