Purity >98%. 2-Acetylphenothiazine (2-APT) is a selective, cell-active inhibitor of NADPH oxidase 1 (NOX1) that blocks the generation of reactive oxygen species (ROS) in HT-29 cells with an IC50 value of 0.129 μM. It does not affect xanthine oxidase-dependent or mitochondrial ROS generation. 2-APT prevents ROS-dependent formation of ECM-degrading invadopodia in colon cancer cells. It also abolishes collagen-induced superoxide production by platelets (IC50 = 306 nM), preventing platelet aggregation and thrombus formation. 2-APT protects beta cells from cytokine-induced apoptosis by inhibiting NOX1. 2-APT can also activate the human transient receptor potential ankyrin 1 (TRPA1) nociceptor at 1-30 μM.